I7 920, HT or not?

[bystander]

I've been using an i7 920 @ 3.3-3.4ghz for 1.5 years. I have done some minor overclocking, but lately, I've noticed some games that my CPU has held me back on, so I've started to really try and overclock it. I'm at 4.0ghz now with Prime95 temps of just under 70C.

Recently, I noticed that when I disabled hyper-threading, my temps drop by about 10C, that's very significant. So I decided to see what I'd be losing if I were to disable HT.

I started doing some google searches to find benchmarks comparing the use of hyper-threading to not using it. I saw benchmarks of Resident evil 5 with and without, and to my surprise, the game had about 10% higher FPS with hyper-threading enabled on an i7 920. I kept hearing that HT was useless.

I ran into a couple other reviews that also showed hyper-threading at the same clocks, showed about a 10% boost in 3dmark06 and other desktop apps it even improved more. http://www.guru3d.com/article/intel-core-i7-920-and-965-review/10

So I guess the question is, I can leave HT on at 4.0 ghz and have Prime95 numbers hitting just under 70C, or I can OC my i7 920 further with HT disabled.

But I'm little fuzzy on the Prime95 temps, as if I disable HT, I can only run 4 threads, which may be part of the reason my temps read lower than when it's enabled and running with 8 threads.

What's your thoughts on this? I'm rather new to the idea of pushing my CPU limits and want to get the most out of my i7 920.

 

[bystander]

So I am doing some of my own tests with and without HT.

I have found that my benchmarks are confirming that HT is best left on, which I find surprising by what I see being stated on these forums.

I ran Metro 2033 at Very High, DOF on, Tessellation on and AAA. I have my i7 920 @ 4.11 Ghz with two 6950's with unlocked shaders @ 910mhz/1350mhz (bus interface of x16/x8).

Without HT: I scored 38.78, 40.60 and 38.90.
With HT on: I scored 41.83, 40.92, and 41.89.

I guess the question I need to know is can I allow for higher Prim95 temps, due to it pushing harder than when HT is off and not reflecting real world temps as well? Or should I just accept lower clocks or do you think I can push my OC high enough without HT to be worth doing?

 

[JackNaylorPE]

Games don't benefit from HT, at least today. Many enthusiast MoBos (i.e. Rampage series) have a BIOS profiling feature. What I would suggest is that you set up a BIOS profile w/ HT at about 3.8 Ghz to use as your "everyday working" BIOS profile. I'd set up another one at about 4.0 - 4.2 Ghz or as high as you can go keeping all core temps at or below 72C-ish and use that as your gaming profile.

Select the BIOS profile you wt to use at boot time. And yes, P95 temps will be 7 - 10C lower with HT turned off.

 

[bystander]

Games don't benefit from HT, at least today. Many enthusiast MoBos (i.e. Rampage series) have a BIOS profiling feature. What I would suggest is that you set up a BIOS profile w/ HT at about 3.8 Ghz to use as your "everyday working" BIOS profile. I'd set up another one at about 4.0 - 4.2 Ghz or as high as you can go keeping all core temps at or below 72C-ish and use that as your gaming profile.

Select the BIOS profile you wt to use at boot time. And yes, P95 temps will be 7 - 10C lower with HT turned off.

This is the thing I'm trying to figure out. Why IS hyper-threading giving me higher results in the Metro 2033 benchmark. Why IS it giving better performance for the Resident Evil 5 benchmark I viewed by someone else? Why is it giving better 3dmark06 scores?

People here say it doesn't help. I understand the reasoning, as most games won't use more than 3 cores or barely benefit from 4. Despite this knowledge, real work benchmarks are showing otherwise. At least for CPU bound systems.

Is there something else that hyper-threading helps with?