[Eug]

I'm due (maybe) for a new iMac in 2009, and the 45 nm i7 Nehalem chips seem like those will be in the new iMac then.

However, I'm wondering if it might just be 4-core. It seems from the various descriptions that quad-core will considered mainstream with this CPU. Still, it does seem like a big jump for the iMac line. Whaddya think?

I'm guessing 2-core for the base models, and then higher-end quad-core models. If so, a higher end quad-core be perfect for me. I use some CPU-heavy multi-threaded apps (like video encoding) so having the extra Hz would be great, and having the extra cores would also improve system responsiveness when using these apps (assuming the hard drive and bus are fast enough). I'm also quickly outgrowing my 500 GB internal drive. 1 TB would be nice. (I already have three external desktop hard drives, but I use one as a general backup drive, and another as a Time Machine backup drive. The third one is a small one I just use for specific backups, etc.)

A 10+ GHz 1 TB 24" consumer desktop with 4 GB RAM sounds pretty good.

[Simon]

First off Intel will be releasing a quad-core mobile Penryn by September. Originally the QX9300 was supposed to have a TDP of 45W, but in the meantime Intel has supposedly managed to get the TDP down to 35 W. IOW this CPU has reached iMac levels. The Q9100 with locked multipliers at 2.26 GHz is also coming up soon. In principle Apple could easily use these quad-core CPUs together with an updated Cantiga board to upgrade the iMac at MWSF in Jan 2009. Since the same boards would also support all other socket B dual-core Penryns Apple could have quad-cores at 2.53/2.26 GHz at the top end and dual-cores at 2.93/2.86/2.53 GHz at the low end. There are a lot of options at 35/25 W TDP.

Nehalem (Core i7) will arrive in a mobile version sometime during 2009. One difference with Nehalem is that rather than having two cores per die (like Penryn, Merom, Yonah), it will come with four cores per die. That means a quad-core Nehalem CPU is the baseline (two-core low-end versions will be made available by deactivating two cores on the die). A quad-core Penryn is made by putting two regular Penryn dies on one MCM. This increases the thermal envelope, makes them more expensive, and means separate caches per core pair. On Nehalem the four cores will all share the same L2 cache. If Apple goes with Nehalem and the according Tylersburg/Calpella chipset (will probably be marketed as Centrino 3) I have no doubt that the iMac will go quad-core. Quite possibly across the entire line.

In addition to having more cores Nehalem also offers a lot of other benefits over Penryn/Cantiga. Some are
• SMT
• integrated low latency memory controller
• multi-level shared cache architecture
• performance-enhanced dynamic power management
• QuickPath Interconnect system architecture (formerly "Common System Interface" similar to AMD's HyperTransport) -> no more FSB
• SSE4.2 instructions

But in any event, Nehalem quad-cores on the iMac are at least one year out. I'd expect another refresh between then and now. That one might already bring quad-core iMacs, but they will be Penryn/Cantiga-based.

[mduell]

This table is a nice reference for the upcoming tock/tick cycle.

Originally Posted by Eug 

I'm due (maybe) for a new iMac in 2009, and the 45 nm i7 Nehalem chips seem like those will be in the new iMac then.

I'd expect a Core i7 iMac no earlier than the second half of the year.

Originally Posted by Eug 

However, I'm wondering if it might just be 4-core. It seems from the various descriptions that quad-core will considered mainstream with this CPU. Still, it does seem like a big jump for the iMac line. Whaddya think?

My expectation is a quad core high-end option at the next refresh (in 1Q09) and the majority of the lineup to be quads (all but the bottom/education model) with the following refresh (4Q09).

Originally Posted by Eug 

A 10+ GHz 1 TB 24" consumer desktop with 4 GB RAM sounds pretty good.

Eh, make it 2TB and 8GB.

Originally Posted by Simon 

First off Intel will be releasing a quad-core mobile Penryn by September. Originally the QX9300 was supposed to have a TDP of 45W, but in the meantime Intel has supposedly managed to get the TDP down to 35 W. IOW this CPU has reached iMac levels.

I don't see 45W as a barrier to iMac usage; the X9000 they're currently using in the top-end iMac has a 45W TDP.

Originally Posted by Simon 

That means a quad-core Nehalem CPU is the baseline (two-core low-end versions will be made available by deactivating two cores on the die). A quad-core Penryn is made by putting two regular Penryn dies on one MCM. This increases the thermal envelope, makes them more expensive, and means separate caches per core pair.

On Nehalem the four cores will all share the same L2 cache.

The theoretical advantages of native quad core over MCM (which AMD has made sure the whole world is aware of) are somewhat mitigated by real world issues. The cost advantage is abated by the lower yields with larger dies and the situations where more than two cores need access to the same L2 cache aren't terribly common (and with the large L2 caches on Penryn, making another copy in the other cache isn't a big problem).
Note Nehalem will have separate (256KB) L2 caches per core rather than per pair and an L3 cache shared among four cores. Changes to this configuration may be revealed at the upcoming IDF, but I doubt it.

Originally Posted by Simon 

But in any event, Nehalem quad-cores on the iMac are at least one year out. I'd expect another refresh between then and now. That one might already bring quad-core iMacs, but they will be Penryn/Cantiga-based.

Agree.

[Eug]

Originally Posted by Simon 

But in any event, Nehalem quad-cores on the iMac are at least one year out. I'd expect another refresh between then and now. That one might already bring quad-core iMacs, but they will be Penryn/Cantiga-based.

That was the time frame to which I was referring. Summer 2009 would work best for me. I'm not interested in purchasing at the spring 2009 refresh. October 2009 would also work, but is a bit late for my plans.

Although not absolutely necessary, I prefer my primary desktop to have Apple Care. The current 2.33 GHz Core 2 Duo iMac I have was purchased Sept. 2006. If I sell this say in August 2009 and then purchase another in Sept., that'd be fine. That way it would still have a month of warranty support left over.

Originally Posted by mduell 

don't see 45W as a barrier to iMac usage; the X9000 they're currently using in the top-end iMac has a 45W TDP.

Hmmm... I'm guessing my G5 2.0 20" iMac I had before this had a TDP (in Intel terms) possibly closer to 40-50 Watts. The iMac worked fine, but it had a louder fan. It wasn't exactly loud, but it was noticeable. Mind you, the case was significantly smaller too of course.

Originally Posted by mduell 

Eh, make it 2TB and 8GB.

Heh agreed. Specifically for the 2TB, that would mean 2 x SATA drives, and that's exactly what I'd want. But I get by with partitioned single drives. I don't want a Mac Pro.

Oh and I would hope it includes a Blu-ray burner.

[mduell]

Originally Posted by Eug 

That was the time frame to which I was referring. Summer 2009 would work best for me. I'm not interested in purchasing at the spring 2009 refresh. October 2009 would also work, but is a bit late for my plans.

Although not absolutely necessary, I prefer my primary desktop to have Apple Care. The current 2.33 GHz Core 2 Duo iMac I have was purchased Sept. 2006. If I sell this say in August 2009 and then purchase another in Sept., that'd be fine. That way it would still have a month of warranty support left over.

The current plan for mainstream desktop and mobile Core i7 is 3Q09 and it usually takes Apple a few months to implement (with rare exception where they get a few parts early) so I think expecting to buy in August/September is optimistic. OTOH the dual socket and performance desktop are reportedly ahead of schedule (September 2008 instead of November 2008), so that may move the mainstream/mobile launch up to early Q3 or even Q2.

Originally Posted by Eug 

Hmmm... I'm guessing my G5 2.0 20" iMac I had before this had a TDP (in Intel terms) possibly closer to 40-50 Watts. The iMac worked fine, but it had a louder fan. It wasn't exactly loud, but it was noticeable. Mind you, the case was significantly smaller too of course.

IIRC the 2.0/2.1Ghz G5s (at 90nm) had a TDP over 50W by IBM's methodology, which would be even higher by Intel's methodology. Also note that with Nehalem some of the work previously done by the northbridge moves to the CPU, increasing the CPU's TDP; I'd expect the figures to rise a bit compared to current Intel chip figures.

Originally Posted by Eug 

Heh agreed. Specifically for the 2TB, that would mean 2 x SATA drives, and that's exactly what I'd want.

Nah, just a single drive to keep the enclosure size down. 3.5" drives are already at 1.5TB (announced and shipping this month), so I expect we'll see 2TB in the first half of next year.

[Simon]

Originally Posted by mduell 

I don't see 45W as a barrier to iMac usage; the X9000 they're currently using in the top-end iMac has a 45W TDP.

The X9000 doesn't have a 45 W TDP. It started at 44 W and has actually come down a bit with the new stepping. Also, Apple isn't using the X9000 on the iMac. Similar to the MBA they are using a slightly modified CPU they get custom from Intel. Its TDP could be anywhere between 35 W and 45 W for all we know.

Regardless of all of this, the quad-core Penryn/Cantiga variants should fit the iMac's TDP even without having to put up with iMac G5 style fan noise. I'd be surprised to see no Q9x00 at all included with the MWSF refresh - at least at the top end I would expect one.

And by the time Eug wants to buy a new iMac we should be awaiting quad-core Nehalem iMacs across the board.

[Eug]

Originally Posted by mduell 

IIRC the 2.0/2.1Ghz G5s (at 90nm) had a TDP over 50W by IBM's methodology, which would be even higher by Intel's methodology. Also note that with Nehalem some of the work previously done by the northbridge moves to the CPU, increasing the CPU's TDP; I'd expect the figures to rise a bit compared to current Intel chip figures.

The G5 970FX at 2.0 GHz had a "typical" power rating of 24.5 Watts. My understanding was that the max power utilization of these chips was supposedly a bit less than twice the "typical" rating, which means that the Intel-like TDP should be under 50 Watts.

[Simon]

And those could get quite loud even though the case was larger than today's.

[P]

As I understand it, the dualcore Nehalems (Havendale/Auburndale) will all have integrated GPUs. If the iMac keeps the current setup of using discrete GPUs, that would imply a quad - with the possible exception of a low-end model.

The question is rather when the mobile Nehalems will launch. Recent rumors suggest that it could be as much as a year from now, but hopefully we will know more after IDF. As I'm also waiting for the Nehalem refresh (on my desk there's still a 1st gen iMac G5 - one of the really quiet ones), I'm just as anxious as any of you.

[P]

Originally Posted by Simon 

And those could get quite loud even though the case was larger than today's.

Actually, the 970FX were the last gen (90 nm) - they were reasonably quiet. The first ones were just called 970, and they had a TDP of [email protected] GHz, IIRC. Those were the loud ones.

[Eug]

IBM didn't release TDP numbers AFAIK. They just released a "typical" power utilization number. However, some mention was also made (not in the official public specs) that referenced the max power utilization.

In any case, the rule of thumb was that max power was less than twice the typical. The original 970 was listed as having a "typical" power usage of 51 W at 1.8 GHz.

However, the iMac never used this chip. The first G5 iMac utilized the 970FX, at 2.0 GHz. Typical for the 2.0 was 24.5 Watts, and 50 Watts at 2.5 GHz (although the 2.5 GHz G5 never made it into the iMac either).

But like I said, the G5 iMacs weren't that quiet. They weren't loud, but the Core 2 Duo iMac is almost dead silent. I couldn't make that claim with my G5 970FX iMac. Because the noise wasn't bad though, I might have kept my G5 for longer... if it hadn't been dead slow at apps like Handbrake. Using the default MPEG4 settings of Handbrake 0.71 way back when, I would get 13.6 fps with the G5 2.0, and 67.2 fps with a MacBook Core Duo 2.0. ie. The MacBook was 5X as fast at the same clock speed.

OTOH, I'm still amazed at just how gorgeous the G5 iMac is inside. It has same austere aesthetic inside as it does on the outside. The Intel iMacs I've seen look much more helter skelter inside. (Not that it really matters. Just sayin'.)

[Simon]

Originally Posted by Eug 

OTOH, I'm still amazed at just how gorgeous the G5 iMac is inside. It has same austere aesthetic inside as it does on the outside. The Intel iMacs I've seen look much more helter skelter inside. (Not that it really matters. Just sayin'.)

In a sense it does matter though. The original iMac G5 looked great inside and was nice to take apart, but it was far from cool or quiet. The current iMac is silent, but a real PITA to take apart. On the inside it looks by far not as nice than the original iMac G5, but I would also put thermal engineering above a clean inside. Of course, doing both nicely is what you'd actually expect form Apple. The MP is clean to look at, great to disassemble, and excellently engineered from a thermal POV. I think the one thing preventing Apple from doing the same on the iMac is Steve's urge to make it as thin as possible.

[Eug]

Personally I thought the main reason was time to market.

Anyways, are you trying to suggest that the Intel iMacs have a better thermal design? Cuz I was the under the impression the main improvement was due the CPU, which is Intel's ball, not Apple's.

[mduell]

Originally Posted by Simon 

The X9000 doesn't have a 45 W TDP. It started at 44 W and has actually come down a bit with the new stepping. Also, Apple isn't using the X9000 on the iMac. Similar to the MBA they are using a slightly modified CPU they get custom from Intel. Its TDP could be anywhere between 35 W and 45 W for all we know.

Intel sSpec only list one stepping (M0) at 44W... what's the new stepping? What's being modified for the X9000s Apple gets? If anything the FSB bump should raise TDP.

[Simon]

New stepping hasn't made it to the market yet. From what I have been told you can expect ~40 W. Nothing dramatic, but still a nice improvement.

[P]

Originally Posted by Eug 

However, the iMac never used this chip. The first G5 iMac utilized the 970FX, at 2.0 GHz. Typical for the 2.0 was 24.5 Watts, and 50 Watts at 2.5 GHz (although the 2.5 GHz G5 never made it into the iMac either).

Hmm... Yes, you're right. I mixed up the models a bit, but some searching has put me straight. Anandtech also has some discussion about this here.

Originally Posted by Eug 

But like I said, the G5 iMacs weren't that quiet. They weren't loud, but the Core 2 Duo iMac is almost dead silent. I couldn't make that claim with my G5 970FX iMac.

Many things behind that: The 1st-gen iMac has a 5200U, desktop model, fabbed at 150nm and running very hot without any powersaving modes. It also uses a proprietary chipset which never clocks down. I don't know to which extent the G5 CPU itself will clock down or disable features, but I doubt that it does as much as a Penryn or Merom model Core 2.

[Eug]

So which Nehalem variant? Clarksfield? Auburndale?

Clockspeed? 2.8ish GHz at the top end?

4 x 2.8 could give me over 50 fps for Handbrake encoding. Right now I usually get around 20 fps with my settings. Fortunately, Handbrake does well with multiple cores.

[Simon]

Originally Posted by Eug 

So which Nehalem variant? Clarksfield? Auburndale?

It will be Clarksfield. Auburndale integrates graphics onto the CPU. Apple will stick with dedicated ATI or nVidia GPUs for at least one more iMac generation.


(straight from Intel at IDF 2008)
The mem controller is integrated onto the CPU so there is no more northbridge. IBEX is the new "southbridge". Instead of an FSB there is now this "QuickPath Interconnect" which somewhat resembles AMD's HyperTransport.

Clockspeed? 2.8ish GHz at the top end?

In that ballpark. Maybe even higher. But I don't see Apple putting a 55 W TDP CPU into the current iMac case. It depends what thermal envelopes they end up with for their new 32 nm process.

4 x 2.8 could give me over 50 fps for Handbrake encoding. Right now I usually get around 20 fps with my settings. Fortunately, Handbrake does well with multiple cores.

Fortunately Handbrake and iSquint both scale quite well over multiple cores

[Eug]

Originally Posted by mduell 

Eh, make it 2TB and 8GB.

Now that I think about it, 8 GB would help. I have 3 GB now, and I still end up paging out sometimes. 4 GB would be an improvement, but doesn't give me much of a cushion. However, I wonder if Apple will use SODIMM memory. If so, that's gonna be $$$$. I'm assuming the chipsets will fully support 4 GB modules, and there will still be only two slots. I can only hope they use standard DIMMs though. It would be significantly cheaper, but still expensive.

And that's with DDR2. Right now on Crucial's website, they don't list 4 GB DDR3 modules at all. I guess I could start out with 2x2 GB DDR3, and then upgrade to 4x2 in a couple of years.

BTW, quad 2.8 GHz (with a fast bus) will make Blu-ray playback easier. Hopefully the OS adds the support. Even if I don't get a Blu-ray drive in the iMac, I'm willing to add a 3rd party drive if necessary. However, if they do add the OS support, I would expect that the iMac will have the Blu-ray option by 2009.

Perhaps the Nehalem iMac will ship after Mac OS X 10.6 Snow Leopard with Blu-ray support is released. Snow Leopard is supposed to handle multiprocessor machines better. Conversely, the iMac will likely NOT be able to run Leopard 10.5. PowerPC machines won't be able to run Snow Leopard since that OS is Intel-only, so for the first time end users will have to run different OSes on different machines. Even hacks won't help. Not a huge deal though for most.

Originally Posted by Simon 

It will be Clarksfield. Auburndale integrates graphics onto the CPU. Apple will stick with dedicated ATI or nVidia GPUs for at least one more iMac generation.

Ah yes, forgot about the integrated gfx. Makes sense.

Originally Posted by Simon 

Fortunately Handbrake and iSquint both scale quite well over multiple cores

I wonder how much HyperThreading will help too.

---

This is sounding so much like a Power Mac thread... except these specs are arguably better overall than any Power Mac in existence.

[P]

Originally Posted by Eug 

(Handbrake encoding)

I wonder how much HyperThreading will help too.

For encoding like that - not at all. Possibly the opposite by trashing the cache. Hyperthreading hides read latencies at a branch mispredict - unlikely to be the case in an encoding operation. Of course, if the CPU is starving for memory bandiwdth, it might hide read latencies, but then you're limited by the memory bandwidth rather than processing power.

[Simon]

Originally Posted by Eug 

I wonder how much HyperThreading will help too.

Actually, precisely for encoding jobs like HandBrake or iSquint, I'm wondering if it would be somehow feasible to turn HyperThreading off. I don't think that will be possible though.

[Eug]

I suspect the new bus will prevent memory bandwidth limitations for this purpose, no? At least at the projected clockspeeds anyway.

As for HT (at least with an older Intel CPU):

[mduell]

Originally Posted by Eug 

So which Nehalem variant? Clarksfield? Auburndale?

Clockspeed? 2.8ish GHz at the top end?

4 x 2.8 could give me over 50 fps for Handbrake encoding. Right now I usually get around 20 fps with my settings. Fortunately, Handbrake does well with multiple cores.

Clarksfield for at least the top half of the lineup, perhaps Auburndale for the education model. I'd expect no lower than 2.67Ghz for the top model with an upper bound at 3.2.

It depends which options you use, but I'd expect better than that with Nehalem; I get about 50fps on my 2.5Ghz Penryn quad with the CQR profile and AAC audio.

Originally Posted by Simon 

The mem controller is integrated onto the CPU so there is no more northbridge. IBEX is the new "southbridge". Instead of an FSB there is now this "QuickPath Interconnect" which somewhat resembles AMD's HyperTransport.

Note the mobile version will have a DMI link (same as the current northbridge/southbridge use) rather than QPI to the Platform Controller Hub (the first revision of which is codenamed IbexPeak).

Originally Posted by Simon 

In that ballpark. Maybe even higher. But I don't see Apple putting a 55 W TDP CPU into the current iMac case. It depends what thermal envelopes they end up with for their new 32 nm process.

Note there's about a 10W TDP inflation for Nehalem, because of the memory controller; a 55W Nehalem could work just as a 44W Penryn does.

Originally Posted by Eug 

Now that I think about it, 8 GB would help. I have 3 GB now, and I still end up paging out sometimes. 4 GB would be an improvement, but doesn't give me much of a cushion. However, I wonder if Apple will use SODIMM memory. If so, that's gonna be $$$$. I'm assuming the chipsets will fully support 4 GB modules, and there will still be only two slots. I can only hope they use standard DIMMs though. It would be significantly cheaper, but still expensive.

The mobile chipsets from Intel will continue to support SODIMMs (204 pin for DDR3) rather than DIMMs (240 pin for DDR3). With DDR3 already being demoed at 16GB DIMMs (yay MetaRAM), 4GB SODIMMs should be pretty affordable in 2010.

Originally Posted by Eug 

BTW, quad 2.8 GHz (with a fast bus) will make Blu-ray playback easier.

AFAIK even (modern) dual core machines can play BluRay fine

Originally Posted by Eug 

I suspect the new bus will prevent memory bandwidth limitations for this purpose, no? At least at the projected clockspeeds anyway.

H.264 encoding is relatively sensitive to memory latency (compare an FB-DIMM machine to a DDR2 machine at the same clockrate/number of cores), so the integrated memory controller should help although DDR3's latency will hurt.

[Eug]

Originally Posted by mduell

AFAIK even (modern) dual core machines can play BluRay fine

There was some iffiness with 2 GHz dual-core Intel chips without hardware assist, at least with some software, when playing back high bitrate H.264 Blu-ray. And plus, it pegged the CPUs so multitasking would be problematic.

I'm not sure if Apple is going to be putting much effort into getting significant GPU-assist for Blu-ray playback. If they don't, having 2.8 GHz quad would make things a lot easier to have a machine do CPU-decode for Blu-ray, while still being able to do real work. (Sometimes I like having a movie playing in a window on my second screen while I do other stuff.) You could even use Handbrake and play a Blu-ray at the same time.

I liken it to the days of DVD playback. For pure software playback my old Celeron 400 could do it, but I couldn't do much else with the machine... until I either 1) stuck in a GPU which supported significant hardware assist, or 2) bought a faster CPU.

P.S. Does OpenCL cover any of this, to make it easier to incorporate GPU hardware H.264-assist? Or is it completely irrelevant in this context?

Originally Posted by mduell 

Clarksfield for at least the top half of the lineup, perhaps Auburndale for the education model. I'd expect no lower than 2.67Ghz for the top model with an upper bound at 3.2.

It depends which options you use, but I'd expect better than that with Nehalem; I get about 50fps on my 2.5Ghz Penryn quad with the CQR profile and AAC audio.

Well, my settings are different:

Avg. bitrate 2500 Kbps, x264, Dolby Pro Logic II AAC + AC-3. When I wrote that previous post, I was getting something like 22 fps with my encode. However, it's also content dependent. My current encode is going at 27 fps, on a Core 2 Duo 2.33. So if it scaled linearly with clockspeed and cores, it would be 65 fps with a 2.8 GHz quad-core. So perhaps a ballpark 60 fps guess might be more appropriate... with this particular title.

Now... 2.8 GHz quad sounds good, but if it's 3 GHz next year, I'd be overjoyed.

[mduell]

Originally Posted by Eug 

There was some iffiness with 2 GHz dual-core Intel chips without hardware assist, at least with some software, when playing back high bitrate H.264 Blu-ray. And plus, it pegged the CPUs so multitasking would be problematic.

By "modern" I was thinking 2.5Ghz duals and above... the $400 machines of today.

Originally Posted by Eug 

P.S. Does OpenCL cover any of this, to make it easier to incorporate GPU hardware H.264-assist? Or is it completely irrelevant in this context?

You could do parts of the H.264 decoding pipeline in OpenCL on the GPU; there are players for Windows that use CUDA on nVidia GPUs for almost the entire H.264 pipeline.

Originally Posted by Eug 

Avg. bitrate 2500 Kbps, x264, Dolby Pro Logic II AAC + AC-3. When I wrote that previous post, I was getting something like 22 fps with my encode. However, it's also content dependent. My current encode is going at 27 fps, on a Core 2 Duo 2.33. So if it scaled linearly with clockspeed and cores, it would be 65 fps with a 2.8 GHz quad-core. So perhaps a ballpark 60 fps guess might be more appropriate... with this particular title.

N.b. Nehalem is 30% faster than Penryn at the same clockrate for x264 encoding.

[P]

Originally Posted by mduell 

Note the mobile version will have a DMI link (same as the current northbridge/southbridge use) rather than QPI to the Platform Controller Hub (the first revision of which is codenamed IbexPeak).

Source? I had not heard this.

[Eug]

Originally Posted by mduell 

N.b. Nehalem is 30% faster than Penryn at the same clockrate for x264 encoding.

Interestingly, this was with HyperThreading turned on. Very impressive. From page 4:

"We couldn't disable Hyper Threading so we reached the limits of what we were able to investigate here."

So a 30% improvement in x264 encoding, and a 28% improvement with DivX. This of course was with an L3 cache size of 8 MB, but if the iMac truly does get Clarksfield, it will also have a L3 cache size of 8 MB (not 4 MB) like the chip in Anand's review. However, the article suggests it's the fast L2 speed (at 256 KB per core) that's more important here (and fortunately the iMac should get that too).

With these numbers, I definitely won't get a Penryn quad iMac should such a beast appear. I'll just wait for Nehalem, even if it means going iMac-less for a couple of months after I have to sell my current Core 2 Duo iMac in August 2009. (My warranty is up in September 2009.)

[mduell]

Originally Posted by P 

Source? I had not heard this.

Not the greatest source, but here it is.

Originally Posted by Eug 

So a 30% improvement in x264 encoding, and a 28% improvement with DivX. This of course was with an L3 cache size of 8 MB, but if the iMac truly does get Clarksfield, it will also have a L3 cache size of 8 MB (not 4 MB) like the chip in Anand's review. However, the article suggests it's the fast L2 speed (at 256 KB per core) that's more important here (and fortunately the iMac should get that too).

I don't think it has much to do with the L2/3 cache size (I think QT7 in this benchmark is H.264); H.264 encoding is known to be sensitive to memory latency (see the h264 scores in the SPEC2006 suite for DDR2 and FB-DIMM machines at the same speed) and the integrated memory controller really helps there.

[Eug]

Well, I've read the same thing as what you said before, and it does make sense. However, I was just going by what Anand suggested.

OTOH, with that link you provided, it says that cache makes a big difference for DivX encoding. DivX isn't H.264 of course, but I don't want to completely discount the importance of fast and abundant cache just yet, esp. if it can help compensate for latency issues.

[zykron]

I'm still waiting for all the L2 caches to be unshared/independent.

[mduell]

Originally Posted by zykron 

I'm still waiting for all the L2 caches to be unshared/independent.

What kind of work do you do where a shared cache hurts performance?

[zykron]

I didn't say that.

But people in the PC world keep talking about independent L2 caches.

So, why not improve performance even more and get independent caches?

[P]

Originally Posted by mduell 

Not the greatest source, but here it is.

I guess QPI makes less sense for a strictly one-socket solution, but I don't understand why Intel seems hellbent on fragmenting the marketplace between server and desktop models. Thanks for the link though.

Originally Posted by zykron

But people in the PC world keep talking about independent L2 caches.

So, why not improve performance even more and get independent caches?

The point about independent caches is that you can decrease latency to them, because there is only one client reading from it. Nehalem has indeed cut the L2 latency down to the same 10 cycles the old Dothan Pentium M had (Yonah, Conroe and Penryn had 14, IIRC) but it has also cut down the size of that cache significantly. The risk that you have to out to the much slower (40 cycles) L3 cache is significant. All in all, the new cache setup is better for server apps, but desktop apps & games will likely see a small decrease in speed in this respect unless they really use all 4 cores. The entire rejuggling of the cache hierarchy is likely to play havoc with many optimizations during the transition period.

[mduell]

Originally Posted by zykron 

But people in the PC world keep talking about independent L2 caches.

So, why not improve performance even more and get independent caches?

Independent caches aren't always better; it's a size (avoiding duplication is one consideration here) vs latency issue.

Originally Posted by P 

I guess QPI makes less sense for a strictly one-socket solution, but I don't understand why Intel seems hellbent on fragmenting the marketplace between server and desktop models.

QPI is still in theplan for desktops (same speed for the performance desktops, 75% speed for mainstream desktops), only the mobile platforms will use DMI/PCH setup; probably for power. Who's moving more than 8Gbps/4Gbps to/from the peripheral side of a laptop?

Originally Posted by P 

The entire rejuggling of the cache hierarchy is likely to play havoc with many optimizations during the transition period.

Fortunately there's already an experience base in the industry for this setup (independent L1/L2, shared L3, and on-die memory controllers) with K10.

Another tangential note on the Nehalem cache architecture is that the L1 cache has been slowed from 3 (as in the prior P6 derivatives) to 4 cycles; this is rumored to allow them to push clockrates up.

[Simon]

Originally Posted by Eug 

With these numbers, I definitely won't get a Penryn quad iMac should such a beast appear. I'll just wait for Nehalem, even if it means going iMac-less for a couple of months after I have to sell my current Core 2 Duo iMac in August 2009. (My warranty is up in September 2009.)

While looking at i7 specs and 45nm Penryn refresh benchmarks I was getting the same idea about my MBP. I think I might just keep my current Merom refresh MBP and skip the Penryn refresh altogether. I'll then buy a brand new Clarksfield MBP as soon as they get released.

In the meantime I'll just have play around with the new octo-core RH server I got at work. Now of course if Apple ads more to the Penryn refresh MBP than just the new CPU (like awesome new case, eSATA port, docking port, <insert more wishful thinking here>) I'll probably cave in. I guess we'll know in a couple of days.

[Eug]

Originally Posted by Simon 

I guess we'll know in a couple of days.

What's happening in a couple of days?

P.S. I just sold my MacBook Core Duo too. My G4 800 iBook will have to do for now. I guess I could wait for Auburndale before I get a new MacBook too. My friends are anxiously awaiting the new MBP updates, and don't understand why I want to wait for 2009. The only wrench in that plan is the fact that I get such a good deal on the hardware. (Education discount and I get a free iPod touch.) It's almost worth it for me to buy a new machine now, and then sell it a year from now to get another one.

[Simon]

Originally Posted by Eug 

What's happening in a couple of days?

Hmm, how about new iPods, new MacBooks, new MacBook pros, and possibly even new iMacs. The last one is a stretch though.

[Eug]

Originally Posted by Simon 

Hmm, how about new iPods, new MacBooks, new MacBook pros, and possibly even new iMacs. The last one is a stretch though.

Why do you say that? If by "days" you mean "weeks", then that sounds like what the rumours are pointing to, at least for iPods. I'm not so sure about the MacBooks/MacBook Pros though. October?

[Simon]

I'm expecting new MB(P)s at the latest by Sep 16. But actually I'm hoping for Tuesday.

Of course with my luck that will probably actually happen since on Saturday I'll be leaving for a business trip to China.

[Eug]

Hmm... I'm starting to wonder if I should get a new iMac sooner rather than later. Perhaps I would if they add some decent upgrades, like that Blu-ray drive I was talking about... AND Blu-ray movie playback support in the OS.

But still, fall 2009 would still make the make the most sense given the rumoured CPU upgrades. I'm just not sure I'll have that much willpower to wait that long.

Originally Posted by Simon 

I'm expecting new MB(P)s at the latest by Sep 16. But actually I'm hoping for Tuesday.

Of course with my luck that will probably actually happen since on Saturday I'll be leaving for a business trip to China.

Have fun in China. Maybe by the time you get back we'll finally have those new MB(P)s.

I'm also considering getting another MacBook sooner rather than later. My iBook is fine for surfing, but as you can imagine, its G4 800 can be rather limiting at times. This perception is magnified by the fact I was using a MacBook CD before this. I had originally planned on 2009 for the laptop upgrade too, but if Apple wows us then it may be sooner.

[Simon]

Originally Posted by Eug 

Have fun in China. Maybe by the time you get back we'll finally have those new MB(P)s.

Well fortunately I'm already back. China totally sucked so no new MBP(s) to read about was even more of a bummer.

I guess pretty much everyone is now expecting it to happen on Oct 14. I do wonder what Apple is thinking though. Their time schedule is really weird this year. New iPods for the back to school period and new notebooks for the holiday buying season. Isn't that pretty much the exact reverse of what it should be?

[Eug]

Originally Posted by Simon 

Well fortunately I'm already back. China totally sucked so no new MBP(s) to read about was even more of a bummer.

I guess pretty much everyone is now expecting it to happen on Oct 14. I do wonder what Apple is thinking though. Their time schedule is really weird this year. New iPods for the back to school period and new notebooks for the holiday buying season. Isn't that pretty much the exact reverse of what it should be?

Apple releases their consumer laptops in the fall after school starts most of the time. This year is (presumably) no different. Furthermore, they release their new laptops in the spring, AFTER most departments have spent their spring budgets. You'd almost think it was on purpose.

OTOH, iMac release dates are a little harder to predict. I expect new ones before the holidays, but I wouldn't necessarily count on it.

[Simon]

The thing is that in both 2006 and 2007 Apple refreshed the MB in May. This year they didn't. The current model was introduced in February. That's just too far away for the back to school season.

They simply blew it this year with the MB. I don't know how much of it is to blame on Intel though. Cantiga with X4500 was originally supposed to arrive in June and was delayed by Intel.

[mduell]

Originally Posted by Eug 

Hmm... I'm starting to wonder if I should get a new iMac sooner rather than later. Perhaps I would if they add some decent upgrades, like that Blu-ray drive I was talking about... AND Blu-ray movie playback support in the OS.

But still, fall 2009 would still make the make the most sense given the rumoured CPU upgrades. I'm just not sure I'll have that much willpower to wait that long.

Note that mobile Nehlaem is not expected in Q4 2009 (quads) and Q1 2010 (duals)... I wouldn't expect a release from Apple until 1Q 2010 even if they do go all quad (which is certainly possible, aside from perhaps an education model).

Buy buy buy! The economy needs it.

[shawmanus]

Good thing is quad core mobile processor prices will come down.. When Intel launched desktop quad cores they had 2 models QX6700 at $999 and Q6600 at $851 in late 2006. By July 2007 Q6600 fell to $266.

Similarly for mobile we have QX9300 at over $1000 while Q9100 is at $851. Next Jan we will have Q9000 at $356. I am sure by the time clarksfield releases we will have $250 quad core mobile. At that point entire iMac line should hopefully be quad core.

[Eug]

HP has released a slim desktop with 2.83 GHz Core 2 Quad. TDP is 65 Watts.

http://www.electronista.com/articles....firebird.800/

Bah. I wanted 3 GHz x 4 for my iMac.

[Eug]

According to the Voodoo specs page, the Core 2 Quad 2.83 in the Firebird 803 model is a Q9550 with 12 MB L2 and 1333 MHz FSB, and uses DDR2-800 (PC2-6400). However, Intel lists a 3.0 GHz model, which is the Q9650.

According to Intel's specification sheet, TDP is 95 Watts, but the article I linked in the previous post specifically states that the TDP of the new chips is 65 Watts.

The fastest mobile quad chip is 2.5 GHz, with a TDP of 45 Watts. 45 Watts would be near-silent, but 2.5 GHz just doesn't have the same cachet as 3.0 GHz. 65 Watts is doable IMO, but might have a sometimes audible fan.

[Pierre B.]

Originally Posted by Eug 

The fastest mobile quad chip is 2.5 GHz, with a TDP of 45 Watts. 45 Watts would be near-silent, but 2.5 GHz just doesn't have the same cachet as 3.0 GHz. 65 Watts is doable IMO, but might have a sometimes audible fan.

AI talked not long ago about the possibility of a new cooling system for the iMacs specifically. If so, then this may be the answer. I am too interested in a new iMac but not before it gets four cores.

[Simon]

Intel just refreshed Yorkfield with the low-power s series. That means you can now get quad-core 45nm desktop CPUs at 65W TDP.

Q9550s - 2.83 / 12MB / 1333 MHz / 65W / $369
Q9400s - 2.66 / 6MB / 1333 MHz / 65W / $320
Q8200s - 2.33 - 4MB / 1333 MHz / 65W / $245

Of course Apple has so far never bothered with Intel desktop chipsets. I certainly wouldn't mind a Bearlake iMac with a Q9550 though.

[P]

At those TDPs, they might want to bother. OTOH, the advantage with the mobile versions is that they underclock further if not loaded, which decreases the average noise level (as opposed to the TDP, which correlates to the maximum noise level). Average noise is probably more important than maximum noise to customer satisfaction.