HT on/off?

[リチャード]

So I have the i7 930 @ 3,8Ghz and I've turned HT off.

 

Why? Because most games I play don't use more that two cores anyway, so why have HT on if it halves the speed to 1,9Ghz/thread? I mean, the game doesn't use four threads just because there are more threads available, and two threads @ 1,9Ghz will perform worse than two cores @ 3,8Ghz.

 

So, on a gaming PC... why would anyone bother turning HT on?

[bradscoolio]

People keep this feature on because it doesn't half their frequency.

[tabuburn]

HT are virtual cores and not physical ones. Games tend to like it when HT is off because they are not as powerful as the physical cores and may sometimes offload the work onto the virtual ones which results in a decrease in performance.

 

http://chipreviews.com/cpu/frostbite-2s-limit-6-core-performance-in-battlefield-3/3/

[smjpl]

HT are virtual cores and not physical ones. Games tend to like it when HT is off because they are not as powerful as the physical cores and may sometimes offload the work onto the virtual ones which results in a decrease in performance.

 

http://chipreviews.com/cpu/frostbite-2s-limit-6-core-performance-in-battlefield-3/3/

 

I have asked this exact question before and never got a straight answer. Does having HT on take away from the physical core power? Your reference seems to say yes (for gaming anyway) but I've only had a quick browse so far. The cpu should clock better at cooler temps with HT off shouldn't it? I think i will knock off HT. See what it does for my fps. 

[tabuburn]

I have asked this exact question before and never got a straight answer. Does having HT on take away from the physical core power? Your reference seems to say yes (for gaming anyway) but I've only had a quick browse so far. The cpu should clock better at cooler temps with HT off shouldn't it? I think i will knock off HT. See what it does for my fps. 

HT does not really take away from the actual physical cores' performance. It is just that the virtual cores created by HT are much weaker than the physical ones but games sees them as a core nonetheless and sometimes assigns a workload on them instead of the physical ones.

 

Not sure how HT affects CPU temps though but if I had to hazard a guess, I would say not so much.

 

Glenwing might explain it better.

[リチャード]

HT are virtual cores and not physical ones. Games tend to like it when HT is off because they are not as powerful as the physical cores and may sometimes offload the work onto the virtual ones which results in a decrease in performance.

 

http://chipreviews.com/cpu/frostbite-2s-limit-6-core-performance-in-battlefield-3/3/

That was the smallest difference I've seen.

 

I assume the frequency gets halved since I drop the FPS pretty much to a half in games like WoW, LoL and SCII when I turn the HT on. Though that's considering I have a 1st generation i7 compared to a 3rd in those tests in that link.

[Art Vandelay]

HT lets one thread do work on another thread while the first thread is waiting for a transfer from the memory. It does not reduce the frequency. The only problems it causes are related to games not being designed properly.

[tabuburn]

That was the smallest difference I've seen.

 

I assume the frequency gets halved since I drop the FPS pretty much to a half in games like WoW, LoL and SCII when I turn the HT on. Though that's considering I have a 1st generation i7 compared to a 3rd in those tests in that link.

Frequency? You mean the CPU clock? Disabling HT will not affect CPU clock speeds.