iMac performance, 2.7 i5 vs. 2.8 i7

[JeffD]

I'm hoping for some feedback about choosing one of these processors. I can afford either, but don't want to spend the extra $200 if it doesn't really do much. Looking at performance charts, it looks like there is a notable difference for various kinds of video processing, but not for audio.

For use of PT9, what do you think?

Thanks.

[lancejorton]

It's roughly 50% faster.

http://browse.geekbench.ca/geekbench2/view/415269

http://browse.geekbench.ca/geekbench2/view/473361

From the Apple Store:
Hyper-Threading (Intel Core i7 only) — a technology that allows two threads to run simultaneously on each core. So a quad-core iMac has eight virtual cores, all of which are recognized by Mac OS X. This enables the processor to deliver faster performance by spreading tasks more evenly across a greater number of cores.

[tamasdragon]

For audio work though, I don't think that the improvement will be "twice as amazing"... :)
Of course, the old saying still true: buy the best you can afford
but in this case, I would hesitate too. If it won't improve the pro tools performance substantially, you spared 200 bucks.

[DJKeys]

I went with the 2.8 i7 iMac and it is the fastest machine I have ever had, Mac or PC. I think the performance is worth the extra $200. Also if you check out the refurbished machines, you can save a lot of $ and then get the AppleCare 3 year warranty as well.

-dj

[elicious]

'cept there's a paper at avid which logs the issue
of hyperthreading diminishing rtas perf
instead of helping it.
first noticed on nehalem mac pro's.
e

[CME]

Originally Posted by elicious

'cept there's a paper at avid which logs the issue
of hyperthreading diminishing rtas perf
instead of helping it.
first noticed on nehalem mac pro's.
e

Can you link to this paper? I'll also search for it. I've always assumed hyper threading would help, and wouldn't have thought twice about paying the $200 for the i7, but if it actually could diminish performance I'd like to know.

[elicious]

so here's the meat from "Avid Customer Success";
(that's what they call support now...)

Here is the report on HT on Macs (first observed on Nehalem Mac Pro)

"In the simple example where there’s a single Hyperthreaded physical processor, there are 2 logical processors. Say the audio engine thread needs 80% of the processor to do its work. With Hyperthreading turned off, the audio thread runs to completion and gets the 80% of the core it needs. Lower priority tasks such as GUI drawing get the remaining 20% of the core. The result choppy GUI updates but the audio is not affected. Now turn on Hyperthreading. Both the audio thread and the lower priority GUI thread contend for the same core’s performance. The GUI thread can get up to 50% of the core. Say it takes 30%. This only leaves 70% for the higher priority audio thread and it blows its deadline as it needs 80% to get its job down on time. "

i'm in a gtr sesh all nite,
i'll try to answer your other q later.

e

[JeffD]

Things are never as straight forward as they seem in the strange universe of pro audio. I wouldn't mind spending the $200, even if it didn't make much difference in PT, to get a boost with some other programs. But if it actually performs worse with PT, that's different. Watching attentively.

[tamasdragon]

Of course spending additional 200 dollars on a computer seems like nothing. But, imho if the performance of pro tools is not better with a large margin, I would rather spend that money on ram, or hdd, or acoustic treatment, or...etc.

I realize that it could seen as somewhat childist attitude, but that 200bucks can do more good for me on other things. :)
Not to mention the fact that that 200bucks is actually 400 here in Hungary. (sadly )