Is it possible through the bios to turn off HT ?

just want to know if possible to turn off Hyper-Threading I have a XPS L501X thanks

 

Hi,

yes it is actually. You will need to download and install a modified bios which enables the option to enable/disable HT.

see post #1702 http://forum.notebookreview.com/acer/480992-acer-laptop-phoenix-bios-bios-mod-request-171.html

and follow instructions on the front page:

Basically, create a bootable disk (using a usb driver or something)
http://forum.notebookreview.com/ace...enix-bios-bios-mod-request-7.html#post6280013

copy the bios files including phlash16.exe onto the bootable disk and basically follow the instructions in the readme.txt from the file you downloaded.


btw if you want to re-enable HT, you might have to reset the bios to default, and then reflash the bios again.

 

just curious, why do you want to disable HT?

 

Absent a BIOS mod, you may be able to achieve essentially the same result by using MSConfig's advanced boot options to limit the number of processors to the number of cores.

 

I'm kinda curious as well.

That might work, but I'd assume not. The CPU itself doesn't distinguish between which of the logical threads is the 'real' one and which is the 'hyper-threaded' one. What would more likely happen is that it if you limited it to 4 (assuming 4 core 8 threads), Windows would take the first 4 CPUs it finds and disable the rest, so you'd have the first 2 multi-threaded cores enabled, and the second 2 disabled. Though I don't know this for sure, maybe Windows is smart enough to tell the difference.

 

It's a new Dell laptop with a i5-core 560M. I want to try and see if I can increase my fps in mame/pcsx2 if I were to turn off HT ? Do you think it's possible ? and if so do you think it would increase my fps in those programs ?

I wanted to check here first before trying and did not want to waste my time fiddling in the bios.thanks

 

Windows knows the difference between real cores and virtual cores. Windows will always attempt to spraid workload over real cores rather than virtual cores. This mostly matters whit the new bobcat architecture in combination with Floating-point heavy programs.

I don't see the point in disabling multi threading, though..

Back in the pentium 4 days, multi threading was junk. It would only increase performance on program's written to take poor advantage of modern hardware, it could even decrease performance.
This is not the case anymore, Today, an multi-threaded core is actually make of multiple of each units. I don't have exact numbers, but it should increase performance on programs like cinebench by about 30%. Today, "core" is a very vague term.

http://www.behardware.com/articles/780-6/intel-core-i5-and-core-i3.html

 

Basically, depending on what it's doing at any one particular time, a core can in fact do two things at once. This doesn't happen much of the time but when it does happen obviously you get to do two things at once. This is why you only gain a few percent with hyperthreading.