What to look at when comparing CPU's?

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Coldblackice

[H]ard|Gawd
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...besides arbitrary Passmark/benchmark scores?

For instance, how would you compare Intel CPU's across the years, from x58 up, assuming they're all at 4GHz (and that the onboard GPU features are unnecessary)? What features or metrics would you look to, and how would you equate the performance output of such (generally)?

Sure, the newer CPU's will probably run better, but why, and how could you know (generally) before running bench tests -- what features or elements of CPU architecture would give you a heads-up?

Bonus ?:

How much performance gain/benefit can you expect for increases in CPU cache sizes?
 
I know an i7 4770K is about 4 times faster at encoding with Premiere Pro CS6 than a Q9550.

I usually glance at the passmark scores for a slight idea of where the chips I am looking at stack up.
 
Coldblackice said:
...besides arbitrary Passmark/benchmark scores?

For instance, how would you compare Intel CPU's across the years, from x58 up, assuming they're all at 4GHz (and that the onboard GPU features are unnecessary)? What features or metrics would you look to, and how would you equate the performance output of such (generally)?

Sure, the newer CPU's will probably run better, but why, and how could you know (generally) before running bench tests -- what features or elements of CPU architecture would give you a heads-up?

Bonus ?:

How much performance gain/benefit can you expect for increases in CPU cache sizes?
Click to expand...

For cache size, it really depends on the program.

The more a program can keep the needed data inside the cache, the faster it will run.

If you have a program that constantly causes cache misses on a CPU with a smaller cache, but does not constantly cause cache misses on a CPU with more cache, everything else being equal, the CPU with the larger cache will run that program much faster.

Other things that give you an idea is the the number of PCIe lanes, depending on how many you need, the speed of the memory that is officially supported, the number of channels the IMC supports (dual vs triple vs quad), the extended instructions the CPU supports, etc.
 
There are a lot of things to consider when comparing the different architectures. Determining speed on your own is almost futile and I'm not sure why you would want to.

When comparing the different CPU's you can't compare things such as Cache, certain logic and actual speed (MHz). These things change drastically from generation to generation. Also speed is very software dependent, determine what you want to compare first then generalize an opinion based off of what that piece of software needs.
 
You really have to read reviews to get a real idea of the performance difference. As Trimlock said, you can't really artificially determine the performance difference of CPUs across multiple generations and platforms on specs alone. So read CPU reviews man.

However a quick cheat-sheet would be Anandtech's Bench:
http://anandtech.com/bench/CPU/39

Personally, I've found that the CPU performance reviews over at Xbitlabs to be very helpful.
 
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