[Madrag]

hello all,

I'm interested to know if it's really worth switching from my 6 moths old PM G5 DP 2.0 with the new Dual core G5 2.3?

I suppose it is faster, but how much faster?
Does anyone have a test comparing the two?

also, is it as quiet as my 2.0?

Is it a good switch (or should I stick with the dual processor)?

many thanks in advance for your input...

[Al G]

In my opinion, no, it would not be worth it. The 2.3 won't be much faster.

[darcybaston]

It depends. I've been reading up on DC vs DP (maccentral.com has some insights at http://www.macworld.com/news/2005/10...ysis/index.php) and am discovering that how the CPUs are used can greatly determine the speed advantages.

Some of the concerns include:
-DC share a bus, DP each have their own (DC slower)
-DC each have a new large chip cache (DP slower)
-Threads are handled differently. With multi-threaded apps, DC is better. When the app is not designed that way, DP *may* be better.

DC's throw off less external heat than 2 cpus, but they're warmer internally (if I understand correctly), so they therefore have lower CPU speeds. This is only temporary apparently as it's a new design and industry isn't done evolving that kind of product to be more efficient, consume less energy etc.

GHz to GHz though, a DC 2.3 will be fast than DP 2, logically. And more so because of the large CPU cache (2x1mb vs. 2x512kb) which makes a world of difference. I mean, +-600MHz jump + larger cache will be a very noticeable speed increase. Plus, you've got PCIe in there, which is a better performer. Assuming you don't have too many PCIx addons to replace if you switch. There's also 16GB max memory addressing vs....what is it on the DP...4GB? 8GB?

I have a DC 2.0GHz which I bought on Wednesday, announcement day. The machine is so absolutely quiet, it makes my iBook sound like a rocket engine. I've tried playing games like Halo, doing distributed.net work like RC5, and watched the activity monitor for cpu load as often as I could. And no matter what I do and for how many hours, the fans don't kick on high. They stay a quiet subtle hum. They spin a bit quicker when I've got the clear air-zone plastic thing off, but it's still quiet.

What's also interesting is that when doing RC5-72 crunching work, the client displays progress as a switch between one core to the next, and it uses both to full tilt.

Running Ableton Live 5, or Logic Express 7, my songs used to choke on my older iBook 933MHz (freezing tracks was always necessary) , and now the dual cores don't even fill up to half on either side. VERY NICE CHANGE!

I've never owned a PowerMac before, let alone a 'dual whatever' model. Coming into it at this stage is very exciting, so please take what I say with a grain of, "they guy's post-933MHz-iBook hyper" salt.

[Lateralus]

If you can get almost as much for your DP 2.0 as it would cost you to buy a DC 2.3, then the upgrade would probably be worth it. If you can't, then I'd say hold off for the next revision.

[CatOne]

No way it's worth it -- any increase you get (which would probably be 15% to 20%) wouldn't be offset by the money you'll lose in trading up.

If you really need more performance, because your dual 2.0 ain't cutting it, you should go straight to the quad.

[Madrag]

I hear you!

nice input so far!
I think it may be a mistake to lose money vs the slight increase of speed...
but on the other hand, it's a newer machine, and I suppose if I were able to sell it for a very good price, it would be worth it.

This brings me to another question:
What are the reasons for buying an used DP 2.0? (I suppose the only good reason to buy my used DP is only to get a faster mac with a lower price, right?)

[darcybaston]

More benchmark results:

http://www.macworld.com/news/2005/10...arks/index.php

[andreas_g4]

If the difference spent in $ is compensated with money you get by reduced rendering times or something, do it. If not, don't.

[mduell]

Originally Posted by darcybaston

DC's throw off less external heat than 2 cpus, but they're warmer internally (if I understand correctly), so they therefore have lower CPU speeds.

You appear to be violating the laws of physics and thermodynamics. DC chips don't have to duplicate all of the hardware that a SC chip has; some hardware can be shared between cores.

And more so because of the large CPU cache (2x1mb vs. 2x512kb) which makes a world of difference.

You'll be hard pressed to associate the performance difference in any benchmark to the cache size. There are a few tasks where it will help, but not the majority of the time.

[iDaver]

Originally Posted by darcybaston

I have a DC 2.0GHz which I bought on Wednesday, announcement day. The machine is so absolutely quiet, it makes my iBook sound like a rocket engine.

That's great to hear. I just ordered one. It'll be my first Power Mac since my noisy old Sawtooth that I sold just because it was so noisy (and got a PowerBook instead).

[power142]

The details emerging from IBM about the power management of the 970MP is interesting, so long as it's supported by Mac OS X. In a way, it sounds like a 2.0 or 2.3 DC might well throw off less heat than their DP counterparts, especially when the machine is ran at anything less than full load for both cores.

The extra cache will certainly help in some situations, and I'm interested in that feature myself having seen how much better AMD Opteron chips can perform relative to an Athlon64 chip at the same clocks speed, with 1MB and 512KB cache respectively. In some respects, the extra cache in the DC PowerMacs will make up for some bus contention between processor core and memory controller, but not in all situations.

The other thing to consider is expansion and the memory situation. If you think the PCI-Express slots might be useful to you in the future, that's something. I know I haven't used a single slot besides the AGP slot in my G5 and don't expect to. Finally, the memory you have in your 2.0DP is incompatible with the new machines, so you'd have to buy new memory.

[Todd Madson]

Originally Posted by darcybaston

It depends.
Running Ableton Live 5, or Logic Express 7, my songs used to choke on my older iBook 933MHz (freezing tracks was always necessary) , and now the dual cores don't even fill up to half on either side. VERY NICE CHANGE!

Finally someone who uses multitrack apps I can talk with: I recently tried to stress
out my DP 2.5 and got to 80 tracks and the machine was still acting like "is that all
you've got?" I did 42 stereo in GB = 84 for one arrangement and the damn thing
sounded like an eight tier wedding cake. I was running out of ideas. This was with
multiple softsynths and multiple layered guitar and percussion tracks.

In Cubase, I ended up getting one third in the performance bar with every softsynth
I have running simultaneously. I couldn't peg it. I'll probably hit the limits someday.

The G4/400 was always 100% maxed every time I did a project on that machine.

So yeah, I'd like to "stress" a quad g5.

[darcybaston]

Wow Todd, that's incredible.

If you've got Live, play with a bunch of tracks using their "Simpler+Impulse" combo default softsynth objects. They're a beast on CPU consumption. Much worse than Logic Express. It's the one thing guaranteed to bring a playback down on my iBook. The new G5 devours it no problem (or at least in the 3-5 track ceiling I had with the iBook).

I haven't had a chance to see how many tracks I can load it onto to cause a pause of some kind. You've invigorated me to try!