L3 Cache and MP

Yes and no

L3 is a cheap way to increase performance, but a bigger L2 is much better.

MP will boost software that is programmed to take advantage of it. It will boost multitasking speed even when running several applications that are NOT programmed to take advantage of two CPUs.

Even though acj pretty much answered the question, I'll add my own opinion. Yes multiple processors can help boost the performance. But as far as I can tell, I can really tell the difference only when I do video editing and rendering. Otherwise, I can't really tell the difference in other usage. There still could be performance boost, it's just that it is not significant enough for me to notice.

And for me

I do a ridiculous amount of work in photoshop. Often I run actions on 100+ images, and this can take 30 minutes or more. With Dual CPU's the computer remains extremely responsive while photoshop chugs away (still fast) in the background.

Another common and correct answer to the question is that one 4GHz CPU would be better 99.99% of the time than two [edit] of the same type of CPU at 2GH.

Re: And for me

Originally posted by acj
I do a ridiculous amount of work in photoshop. Often I run actions on 100+ images, and this can take 30 minutes or more. With Dual CPU's the computer remains extremely responsive while photoshop chugs away (still fast) in the background.

Another common and correct answer to the question is that one 4GHz CPU would be better 99.99% of the time than two 2GHz CPU's

Click to expand...

Unless that 4 GHz CPU happened to be a Pentium 4, and the Dual 2 GHz was a G5. Then it would be about half and half.