[Eug]

The weird part is the 2.93 GHz 8-core getting the same score as Core i7, and the 2.66 GHz 8-core getting the same score as Core i5.

As for accuracy:

---

The (simplified) algorithm used to calculate APP consists of the following steps:

* Determine how many 64 bit (or better) floating point operations every processor in the system can perform per clock cycle (best case). This is FPO(i).
* Determine the clock frequency of every processor. This is F(i).
* Choose the weighting factor for each processor: 0.9 for vector processors and 0.3 for non-vector processors. This is W(i).
* Calculate the APP for the system as follows: APP = FPO(1) * F(1) * W(1) + ... + FPO(n) * F(n) * W(n).

The unit of measurement is Weighted TeraFLOPS (WT).

---

So, APP WT needs double precision.

The Mobility Radeon HD 4850 alone in the quad iMacs is theoretically capable of 8000 Gigaflops of single precision FP.

I was assuming that downloadable Mac OpenCL Benchmark app was single precision, but it was a major PITA to get the thing to actually work. Maybe someone will create a much better GUI-ified version soon, because that the present time it's useless for us n00bs.

[Eug]

Screen flicker on 27" iMacs

Video 1
Video 2 <-- Ignore the big flashes. I think he was taking snapshots with the camera flash.

FWIW, I did not see this in the 15 minutes in the store I had with the 27" (Core 2 Duo 3.06).

[Simon]

Originally Posted by Eug 

Video 2 <-- Ignore the big flashes. I think he was taking snapshots with the camera flash.

It looks like his camera is an iPhone though.

[Eug]

Not sure, but you could be right. However, if you are right, I don't understand what those big flashes are then, because those haven't be reported AFAIK.

[Simon]

Sure looks like an iPhone to me. Also, the flash appears to be coming from the bottom left, but definitely not from the phone.

[Eug]

BareFeats iMac Core i7 benchmarks vs. Mac Pro 2.93 Octo and Mac Pro 2.93 Quad, as well as iMac Core 2 Duo 3.06.

Why is Compressor so much slower on the iMac? BTW, the Core 2 Duo looks like ancient technology in this comparison.

[P]

Originally Posted by Eug 

BareFeats iMac Core i7 benchmarks vs. Mac Pro 2.93 Octo and Mac Pro 2.93 Quad, as well as iMac Core 2 Duo 3.06.

Why is Compressor so much slower on the iMac? BTW, the Core 2 Duo looks like ancient technology in this comparison.

Main memory bandwidth is the only logical answer. Note that the iMac can take faster DDR3-1333 RAM to make up for some of the difference.

[P]

Originally Posted by Eug 

Screen flicker on 27" iMacs

Video 1
Video 2 <-- Ignore the big flashes. I think he was taking snapshots with the camera flash.

FWIW, I did not see this in the 15 minutes in the store I had with the 27" (Core 2 Duo 3.06).

If you check Apple Support Forums, they have a million of these. Almost everyone seem to agree that it's a software thing, though, as it occurs on external displays as well - one person even recognized the same thing from his Windows installation where a certain version of the ATi driver caused it.

Anyway. Mine has flickered like that once. A lot of people seem to have fixed it with a simple PRAM reset. We'll see what happens - note that the drivers that came with my machine were newer than those in 10.6.2, dated Nov 4th.

[Eug]

I read this over on another forum:

For anyone interested in upgrading their new 27" iMac with an SSD drive, it's a fairly painless process, I found it to be a little easier than the previous 24" iMac (refer to the teardown guide at ifixit.com if you're interested in the process of taking it apart).

I installed my SSD drive but noticed that when I was installing Snow Leopard the system fans seemed to be running very high. I discovered the 'HDD Fan' was ramped up to over 3200RPM. Remembering back to installing the SSD drive, there is a connector connected to the jumper block of the original hard drive (in addition to the SATA and Power cables). I traced this wire back to the motherboard and discovered that it is marked as 'HDD Temp'. I'm not quite sure how Apple gets a hard drive temperature from the jumper block of the hard drive but after shorting the two terminals of this connector with a little piece of wire the fans behave normally.

[Simon]

Originally Posted by Eug 

I'm not quite sure how Apple gets a hard drive temperature from the jumper block of the hard drive but after shorting the two terminals of this connector with a little piece of wire the fans behave normally.

OTOH that could also mean the HDD fan will never ramp up regardless of what temperature the SSD reaches. The SSD itself won't create a lot of heat, but we do know the new iMac internals can become very hot. I'm not so sure having that fan never ramp up at all is such a good idea.

Regarding heat, it will be interesting to see how many GPUs go bad on the new iMac. The last iMacs had their fair share of problems with GPUs overheating. The new iMacs seem to be very quiet, but also run very hot under load.

[P]

True, but the HD is not in a hot spot of the iMac - in fact, it is in the coolest part of it. The CPU and the GPU, and their heatsinks, are in opposite areas of the iMac and the HD is in the center. The only heat-generating thing in any reasonable proximity to the HD is the PSU (which does get hot when you torture the machine). I don't love the idea of disabling the thermal sensor, but the risk should be minor.

Anyway: Replacing the optical sounds like a much safer option. You could even fit two or three in that space.

Final warning for replacing the HD: It is a 1/3 height drive, not the more common 1/2 height, so if you're replacing with a different drive, make sure that it's 1/3 height or lower. Obviously an SSD is much smaller than that.

[Eug]

No, it's not mine.

Originally Posted by P 

Main memory bandwidth is the only logical answer. Note that the iMac can take faster DDR3-1333 RAM to make up for some of the difference.

Anyone try this yet?

[Eriamjh]

Originally Posted by Eug 

I read this over on another forum:

Remembering back to installing the SSD drive, there is a connector connected to the jumper block of the original hard drive (in addition to the SATA and Power cables). I traced this wire back to the motherboard and discovered that it is marked as 'HDD Temp'. I'm not quite sure how Apple gets a hard drive temperature from the jumper block of the hard drive but after shorting the two terminals of this connector with a little piece of wire the fans behave normally.

Be aware that Apple is now using a built-in temp sensor for the HDDs, hence the cable. If you replace the drive, you need to use the same brand as the original.

Proprietary Cable can put the brakes on upgrading Late '09 iMacs. | Other World Computing Blog

[P]

I just installed Bott Camp on a spare partition. Except SP3 not installing and the Miagic Mouse not working, it worked fine, and I proceeded to run GPU-Z.

Drumroll please...

The clockspeeds of the Mobile Radeon 4850 are...

503 MHz Core and 850 Mhz Memory.

For comparison, the stock Mobile Radeon is 550/750, and the stock desktop 4850 is 625/993. Compared to the desktop chip, we've lost a 19% of the core speed and 14% of the memory bandwidth. Compared to the mobile chip, we've lost 9% of core but gained 13% of the memory bandwidth. The interesting bit is that the ratio of core processing capacity to memory bandwidth is now much closer to the desktop model than the mobile model. It's underclocked by some 14-19%, depending on whether it's bandwidth or shader limited.

[Eug]

So, 0.855 Teraflops, which is actually faster than I was predicting (because of the much faster memory).

I still don't understand why it needs to be 503 MHz and not 550 like the Mobility version though.

[P]

Hm. Another site reports the default mobile clockspeeds as 500/850, almost exactly what the iMac has. Neither sources their data, and ATi isn't telling.

[Eug]

I don't really like this mouse though. Maybe it will grow on me.

[Eug]

Here are the benches that go along with that Cinebench screengrab:



Basically, the Core i7 is over 3X as fast as my Core 2 Duo MacBook Pro, and 25X as fast as my iBook.

BTW, I ran Handbrake H.264 encoding too, and got worried because the Core i7 was taking longer than the MacBook Pro. I then realized it was because I copied Handbrake to the iMac from my Cube... and thus was running Handbrake under Rosetta. So I installed the Intel version, and again, the iMac is well over 3X as fast as my MacBook Pro. Using the default 2-pass x264 settings I was able to encode 10 minutes of a DVD cartoon in about 2 minutes.

This is gonna be awesome. One of the main reasons I got the quad was for video encoding.

EDIT:

This is from Bare Feats:

[EndlessMac]

If anyone is interested MacWorld has a review of the 27" iMacs.

[Eug]

I have not yet had any screen flicker issue.

BTW, if anyone cares, the stock DDR3 1067 memory I got is Samsung 7-7-7. That's exactly the same memory speed I got from Crucial. Installed before even the first boot, and working fine.

Has anyone tried DDR3 1333 yet?

[Love Calm Quiet]

Originally Posted by EndlessMac 

If anyone is interested MacWorld has a review of the 27" iMacs.

Rating: 4.5 mice.
Summary: "With the new 2.66GHz Core i5 iMac and the 2.8GHz Core i7 iMac, Apple has not only blurred the line between consumer and professional systems, it's darn near erased it." [Obviously the Mac Pro will be taking its own "giant leap for mankind" at its next upgrade.]

I remember how in ancient times I actually subscribed to MW. This review is so shallow (compared to what one get from just a little time at MacNN): Mostly a list of features and specs put into prose. I am reminded why MW is passé - not worth the bother to bookmark.

Only benefit to me was that I got one more confirmation that the $1699 model is all *my* purposes need, and that position (relative to light) in the room is going to be key.

[mduell]

Originally Posted by Love Calm Quiet 

Rating: 4.5 mice.
Summary: "With the new 2.66GHz Core i5 iMac and the 2.8GHz Core i7 iMac, Apple has not only blurred the line between consumer and professional systems, it's darn near erased it."

What ridiculous drivel. Apple finally offers a consumer desktop (with heavily limited expansion/upgradability) instead of a laptop without a battery and they're gushing over like it's a borderline professional system? Please, it's a run of the mill desktop in everything but bling.

[Love Calm Quiet]

@Eug:
"BTW, I ran Handbrake H.264 encoding too, and got worried because the Core i7 was taking longer than the MacBook Pro. I then realized it was because I copied Handbrake to the iMac from my Cube... and thus was running Handbrake under Rosetta."

I'm trying to guess how painful it's going to be to postpone upgrading a bunch of my PPC-based software (MS Office, FileMaker Pro, etc), and I was hoping that getting at least a Core i5 would (via Rosetta) give me some boost from my aging 1.5GHz PowerBook. But your Handbrake description there makes me think that (even on a Core i7) Rosetta emulation is going to be sluggish.

Anybody got anything to report on speed of Rosetta on C2D & i5 compared to running native on some PPC machines?

[Love Calm Quiet]

@Eug:

[P]

Originally Posted by Love Calm Quiet 

@Eug:
"BTW, I ran Handbrake H.264 encoding too, and got worried because the Core i7 was taking longer than the MacBook Pro. I then realized it was because I copied Handbrake to the iMac from my Cube... and thus was running Handbrake under Rosetta."

I'm trying to guess how painful it's going to be to postpone upgrading a bunch of my PPC-based software (MS Office, FileMaker Pro, etc), and I was hoping that getting at least a Core i5 would (via Rosetta) give me some boost from my aging 1.5GHz PowerBook. But your Handbrake description there makes me think that (even on a Core i7) Rosetta emulation is going to be sluggish.

Anybody got anything to report on speed of Rosetta on C2D & i5 compared to running native on some PPC machines?

The comparison was C2D native versus i7 on Rosetta. I think that the examples you quote will be faster on the iMac, for the simple reason that it has a fullsize 7200 RPM HD as opposed to the 5400 or 4200 RPM drives in the PBG4.

[Eug]

Ironically, I ran Office 2004 on my previous Intel MacBook because it felt like it loaded faster under Rosetta than the native Office 2008. Office 2008 is quite bloated. OTOH, Office 2008 feels fast enough on my Core i7 iMac.

Office 2004 Benchmarks on Intel-based Macs

[Love Calm Quiet]

Originally Posted by Eug 

Ironically, I ran Office 2004 on my previous Intel MacBook because it felt like it loaded faster under Rosetta than the native Office 2008.

THAT is exactly what I needed to know - that one can do fine running 2004 via Rosetta.
[ I've really no interest in upgrading (sending $ to Redmond) & I fortunately don't have to *make a living* in Word, just the occasional concession to some bureaucrat. ]

:: made my day ::

[Eug]

BTW, you can download an update from MS to get docx support in 2004, so there isn't really any big reason to "upgrade" to 2008 anyway.

[amazing]

OTOH, seeing stuff like the following makes me rather sad:

Core i7 iMacs showing up DOA -- including ours -- Engadget

[Love Calm Quiet]

Originally Posted by amazing 

OTOH, seeing stuff like the following makes me rather sad:

Agreed.

Apparently some sort of glitch. But who-knows-what. And *strange* that it's currently only being mentioned for the i7s (a rather select sub-species - and not in my budget).

When I first saw headline I thought maybe it was some sort of *heat* issue. Then I noticed it was DOA: suggesting shipping damage - and I couldn't begin to imagine why the packaging/etc. should be any different between i7 and i5 (or even versus C2D).

If Apple can get their QA issue solved quickly we may *never* know the "why"

[Simon]

Or how about this? Although the box shows no sign of damage at all, the glass plate in front of the screen is cracked on arrival on a growing number of i7 iMacs. There's some speculation about fastening tolerances and thermal expansion.



Hardmac.com - iMac Core i7: New Problems

On the bright side, there are going to be a lot of new iMacs for cheap in the refurb store pretty soon.

[P]

It actually looks like it's only the front sheet (which looks like glass in that picture, but doesn't on mine) that is cracked, in which case it's five minute operation to replace. The way the attachment works (according to ifixit) is that two tabs hook in to the bottom, and it is then held by magnets. They even note that it moves easily to the side - that pretty much rules out cracking from tension in the fastening. No, I think it's a collision with an outside object. The new iMacs have MUCH less packaging than the old ones, and only the corners of the iMac are padded at all (with styrofoam). The front of the display is fairly close to the edge of the box, and I can easily see that box distending enough to get a smash.

Hm. Maybe if they were to add some beveling on the inside of the box?

[Love Calm Quiet]

But I have to wonder again:

Why is this (and the "DOA" / "start-up chime only" phenomenon) being reported as a "Core i7" issue? Surely Core i5 and C2D should have exactly the same packaging (and, for "DOA" report, connector/cable) as the Core i7, shouldn't they?

[Correct me if I'm misunderstanding the reports.]

[Spheric Harlot]

I'm thinking a single shipment of the machines getting a nasty whack due to weather/turbulence/whatever.

[Eug]

Using a 27-inch iMac as an external display

To use a 27-inch iMac in Target Display mode with another computer as the source:

1. Make sure both computers are turned on and awake.
2. Connect a male-to-male Mini DisplayPort cable to the Mini DisplayPort on each computer. The 27-inch iMac will enter Target Display Mode and display content from the source computer.
Note: If you are connecting two 27-inch iMacs, connect a Mini DisplayPort cable to each computer and press Command + F2 on the 27-inch iMac keyboard that you will use as an external display.
3. To leave Target Display mode, press Command + F2 on the keyboard of the 27-inch iMac that is in Target Display mode. To return to Target Display mode, press Command + F2 again.

----

I suspect we'll have only dual-core in the 21.5" iMacs for quite some time, although they'll be labelled Core i5.

[Eriamjh]

Originally Posted by Love Calm Quiet 

But I have to wonder again:

Why is this (and the "DOA" / "start-up chime only" phenomenon) being reported as a "Core i7" issue? Surely Core i5 and C2D should have exactly the same packaging (and, for "DOA" report, connector/cable) as the Core i7, shouldn't they?

[Correct me if I'm misunderstanding the reports.]

I don't think that the i5 or C2D models are reporting the problems because they aren't having them. I haven't read about any other models having this problem.

I think only the Core i7s are being shipped express from China. The others probably came by boat or at least were shipped in bulk. Same packaging, different shipping methods.

It could be a shock issue and not really a packaging issue. If the package isn't damaged, maybe impact from dropping is shocking the glass causing the fractures? Maybe a tech is purposely breaking the i7s in China before they leave?

[mduell]

Anyone know if they use shock sensors on the pallets/ULDs they use to express ship new Macs?

[Eug]

Power utilization:

Off - 2 Watts
Sleep - 2-4 Watts
Idle, screen off - 55 Watts
Idle, min brightness - 71 Watts
Idle, mid brightness - 96 Watts
Idle, max brightness - 157 Watts

With screen set to mid brightness:

Booting up - Up to 184 Watts
Transfer file over network - 125 Watts
Cinebench OpenGL - Up to 142 Watts
Cinebench multi-CPU - Up to 196 Watts

Cinebench multi-CPU with screen at max brightness - Up to 257 Watts.

[Simon]

Originally Posted by Eug 

I suspect we'll have only dual-core in the 21.5" iMacs for quite some time, although they'll be labelled Core i5.

That's pretty much in line with Intel's plan. Penryn -> Arrandale, Wolfdale -> Clarkdale, Yorkfield -> Lynnfield. Apple can keep the low-end iMac cheap with dual-core Clarkdale while using Lynnfield on the more expensive models.

Since Clarkdale is a whole lot cheaper than Penryn was, once Clarkdale iMacs arrive Apple should be able to deliver more bang for buck compared to the previous 20"/24" iMacs. Note the effect Lynnfield vs. Penryn had on the high-end model price-performance ratio already. Ahh, the glory of using actual desktop CPUs in a desktop computer (or at least what Apple calls a desktop).

[P]

The prices above mean that the i5 660 replaces the E8500 at the same prices as the i5 750, and the 670 replaces the E8600 at a price equivalent to the i7 860. IMO, this means that especially the 670 is an absolutely terrible deal unless you're happy with Intel integrated graphics. A cheaper iMac using one of the lower end models, sure, but the 750 and 860 are better deals than the two top options.

The latest word is that Core i3 won't have Hyperthreading after all, which directly contradicts what Intel said this summer. We'll see, I guess.

[Eug]

So nobody has tried DDR3-1333 MHz memory yet?

Originally Posted by P 

The prices above mean that the i5 660 replaces the E8500 at the same prices as the i5 750, and the 670 replaces the E8600 at a price equivalent to the i7 860. IMO, this means that especially the 670 is an absolutely terrible deal unless you're happy with Intel integrated graphics. A cheaper iMac using one of the lower end models, sure, but the 750 and 860 are better deals than the two top options.

The latest word is that Core i3 won't have Hyperthreading after all, which directly contradicts what Intel said this summer. We'll see, I guess.

Intel's naming seems intentionally misleading IMO.

They should have something like this:

i3 - 2 cores, 2 threads
i4 - 2 cores, 4 threads
i5 - 4 cores, 4 threads
i7 - 4 cores, 8 threads
i9 - 8 cores, 16 threads

[Simon]

Actually, it would be nice if their naming reflected mobile vs. desktop CPUs, that is at least give some kind of indication of TDP. But as it is now i5 can mean anything between 35W and 95W. In this respect it's no better than the previous C2D moniker.

[Eug]

True, but they could just say "i5 mobile" or something like that. Or better yet, just i5 2.66 or i5 2.16 or something like that. Most people wouldn't understand TDP anyway, but they would understand that an i5 2.16 would be slower than i5 2.66 if the only significant difference were the clock speed (and not the number of physical cores). In this context, the actual TDP value doesn't matter at all to the average consumer.

However, instead, they chose to totally confuse the general public. It seems completely ludicrous to have the same "i5" come in both 4-core and 2-core flavours.

[P]

The logic, at least as I understood it, was that the i7 was 8 threads, the i5 was 4 threads, and the i3 was 4 threads without the turbo. The Pentium G series would then be the 2 thread version of the Nehalem core (also without turbo). Of course the mobiles completely broke this - specifically, the i7 600 series Arrandales broke it.

[mduell]

Intel's processor naming scheme has been a mess ever since they switched from frequencies to numbers. AMD actually did quite well with their numbering scheme for a while with only a few idiosyncrasies.

Fortunately Intel's numbering scheme is so bad I think they'll restart/redo it in a year or so with Sandy Bridge. A massive collpase of the number of variants would make it a lot easier*, but with their monopoly power to price discriminate I think they're going to stick with the huge array of options they have now.

* I think the market could be well covered by a dozen each desktop, laptop, and (2P) server/workstation models.

[Eug]

This is from the Windows side, but I like the graph, as a demo of HT vs. non-HT.



Note also though that in the iMac, Core i7 is 5% faster clocked than Core i5. (This graph would be roughly equivalent to Core i7 vs. a hypothetical faster Core i5 at the same clock-speed as Core i7.)

[Eug]

Very simple artificial test of course, but nonetheless the 3.33 GHz Core 2 Duo is not very impressive, compared to the cheaper Core i5.

[Simon]

I fully agree. I cannot see why a prospective 27" buyer would spend $200 on the E8600 when you can get an i5-750 plus better graphics for $300.

[Eug]

So, I had a rip of a WWII era movie that a friend wanted to watch. Since he's not a geek I decided to transcode it to DVD instead this morning. Since it's in PAL format and I needed NTSC, Toast gave a warning message that it could take a very long to encode. I said OK and let 'er rip. By the time I got back from my brushing my teeth and a shower, it was done.

Quad-core Nehalem rocks.

[Love Calm Quiet]

Originally Posted by Eug 

Screen flicker on 27" iMacs

Video 1
Video 2 <-- Ignore the big flashes. I think he was taking snapshots with the camera flash.

FWIW, I did not see this in the 15 minutes in the store I had with the 27" (Core 2 Duo 3.06).

Well, I got the same machine now (27" C2D 3.06) and after a few hours run-time I started occasionally seeing exactly what Video 1 (above link) shows
Hasn't started it this morning again (yet), but after hours of file transfer and upgrading of apps and prefs, I'd sure like *not* to have to return this !