true difference between i7 & i5

[crazymonkeyzero]

I've had this question for some time now and was hoping someone could answer it; is a intel core i5 practically just an i7 with hyper threading disabled? In in other words, if I were to 'disable' hyper threading on a i7 2600k and ran it at the same clock speeds as a i5 2500k, would they perform nearly identical in benchmarks/ real world applications and programs. Thanks for the clarification.

 

[AtenRa]

Yeap, they are the same chips. Core i5 has less L3 Cache and no HT, everything else is the same.

 

[Yuriman]

That's the most significant difference. The i7 also has a little more L3 cache, 6mb vs 8mb. There might be some small feature differences but I don't know of any offhand.

EDIT: Beat me to it!

 

[crazymonkeyzero]

Thanks for the reply guys. I was going to run some software which relies heavily on clock speed and cores, however, does not support hyper threading, so this will help me decide to go with an i5/ non hyper threaded chip to save some money.
Also what exactly does the extra cache help with in a processor?

 

[Yuriman]

The benefits of a larger L3 cache depend on a few factors, but a simplified example: If your code fits in the L3 cache of the i7 but not in the cache of the i5, it will run significantly faster on the i7 because it won't need to be fetched from RAM.

More cache can in some cases give a nice performance boost, but 8mb vs 6mb doesn't do much for most workloads.

 

[PrincessFrosty]

Thanks for the reply guys. I was going to run some software which relies heavily on clock speed and cores, however, does not support hyper threading, so this will help me decide to go with an i5/ non hyper threaded chip to save some money.
Also what exactly does the extra cache help with in a processor?

Wait...isn't hyper threading transparent to applications? I was under the impression that no software support was required by applications for hyper threading, only from operating systems.

If an application is multi-threaded it should be able to make use of hyper threaded cores providing it can start enough threads to use all of the available logical cores, although the OS may assign threads to physical cores before hyper threaded ones for performance reasons.

Either that or my understanding of hyper threading is way off :s

 

[ShintaiDK]

Thanks for the reply guys. I was going to run some software which relies heavily on clock speed and cores, however, does not support hyper threading, so this will help me decide to go with an i5/ non hyper threaded chip to save some money.
Also what exactly does the extra cache help with in a processor?

You got it all wrong. All applications as such supports hyperthreading. It got nothing to do with those.

What you need to figure out is basicly if your application(s) use above 4 threads and if the price premium is wiorth it for the extra performance benefit of HT in those cases. The i7 is also clocked at 100Mhz more.

 

[PrincessFrosty]

I think the i7s overall headclocking room is higher? I believe the i5's tend to be comfy around 4.5Ghz with air, my i7 2600k is comfy on 4.7Ghz but will go higher, some hit 5Ghz with decent air cooling and some luck.

 

[aaksheytalwar]

Real differences are usually felt outside gaming, in pro tasks.