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Interesting article about Photoshop and Multi-Core...
http://blogs.adobe.com/jnack/2006/12/photoshop_and_multicore.html
(sorry if this has been posted already)

Gives me the impression that for Photoshop, one would be better off with a faster four core machine than a slower eight core, even with CS3. Video rendering is of course a different story.

It makes a lot of sense. I imagine most people will notice SLOW DOWN if they moved from a 3ghz quad to a 2.66ghz octo setup; the vast majority of applications on all platforms will only thread so much, and single core speed is important.

Take PC games for example: Something like Half-Life 2. This game has two threads, one for graphics and one for audio. On a single core 3.2ghz CPU it runs quite nice. If you then installed it on a dual core 2.66ghz CPU you get about a 50% improvement in speed, because of the slower clock speed. If you then moved the game to a quad core system you see around 5% improvement in speed. The game simply isn't aware of the extra cores. Now, say the quad is only clocked at 2ghz, HL2 would run MUCH SLOWER on a quad system than a dual system - because each core in the quad is running far slower than a dual or single setup.

The initial release of Intel Quad chips are likely to be fairly slow (slower than the current 3ghz dual core xeons anyway), meaning you'll only get a boost in performance in programs that are 1) have lots of threads 2) are designed to split workload over more than 2 cores.

I guess with lots and lots of cores, you get the advantage on a system running many large programs a better balance and over all performance. If you run 8 programs that each never really require more than a 2ghz CPU, it'll OS X would never, ever slow down. But the chances are you're going to have some programs running that need a little more beef (PhotoShop as an example). I'd be suprised if PhotoShop benchmarks on the new octo setups will be any faster than the current quads; I'd actually almost expect it to run slower.
 
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