Why clock speeds are not the best indicator or CPU ability's

[Rokin]

So here is the story, i got into an argument with a buddy of mine about cpu's and price per performance and the x99 motherboard with the intell 5960x proccessor came up and with it his side of the argument stating that clock speeds are the only thing that matters as far as processors and that the 5960x was slow because of its 3GHz clock speed. Then i said clock speed was not the only thing that matters and i could not come up with reasons why, it was just what i was told. So i'm here looking for some higher knowledge people to educate me on why clock speeds are not the only thing that matters. Or if i'm wrong and it is in fact the only thing that matters. The AMD processor in the list below is the one he was comparing to the i7- 5960x and the i5 is my personal processor. As always thanks for the information. 

 

AMD FX-8350 Black Edition Vishera 8-Core 4.0GHz (4.2GHz Turbo) Socket AM3+ 125W (150$) 

 

 

Intel Core i5-4690K Devil's Canyon Quad-Core 3.5GHz LGA 1150 (250$) 

 

Intel Core i7-5960X Haswell-E 8-Core 3.0GHz LGA 2011-v3 140W (1000$)

 

 

 

[Alim]

It also depends on IPC and instruction sets.

[CatzRuleZWorld]

IPC: Instructions Per Clock

AMD CPUs don't have very good IPC compared to Intel's.

This is the same reason that older CPUs at the same speed as new CPUs aren't nearly as good.

[Enderman]

as long as you are comparing two CPUs with the same architecture the clock speed is directly related to single core performance

but in multithreaded applications more slower cores can perform better than few fast ones

[Blebekblebek]

you have long material to read about

http://en.wikipedia.org/wiki/Megahertz_myth

http://en.wikipedia.org/wiki/Instructions_per_cycle

http://en.wikipedia.org/wiki/Performance_Rating

http://en.wikipedia.org/wiki/Cycles_per_instruction

 

if you want simplified things, just say IPC on intel is twice than AMD (or older technology by intel itself)

and when he asks prove, throw BENCHMARK number at him.

[Sauron]

If he was right, my pentium 4 from 13 years ago would be faster than a 5960x.