- Joined
- Aug 19, 2004
- Location
- Florida
I fixed a long standing problem I have had with Hyperthreading and wanted to share the information in a more prominent place than the end of a long thread. There are a lot of folks running a HTT capable P4 on an Abit board with SATA disks and some of them may have had this problem. All of the credit for this fix goes to antichrist, who did the research and found the answer. Thanks again t0m.
When Windows XP is installed, it checks your motherboard to see what type of HAL (Hardware Abstraction Layer) should be used. With some hardware combinations and BIOSes (I am still researching this), Windows XP, using its own judgement, might select an inappropriate HAL. Once the HAL is set, it cannot be changed without a new or upgrade installation of Windows XP. To check the HAL you have go to Start|Control Panel|System|Hardware|Device Manager|Computer. There are several HAL's available for windows to use and if it picks the wrong one, you will lose functionality. For example, my problem was that I was obliviously using the "MPC uniprocessor" HAL which disables hyperthreading. So even though HTT was enabled in BIOS, Windows did not recognize, or use two CPUs. (Task manager showed one CPU graph.)
There is a way to force Windows to use the HAL you want. During any installation (new or upgrade), when setup asks you to hit F6 to install SATA drivers, hit F5 (if you have a SATA drive hit both F5 and F6). The F5 key prompts you to choose a HAL. Use the arrow keys to navigate the list. For my case I picked "ACPI multiprocessor PC". Next, Windows will ask for the floppy with your SATA driver and installation proceeds normally. Afterwards, don't forget to reinstall chipset, LAN, sound and video drivers and windows updates.
With hyperthreading enabled I see up to a 33% increase in CPU benchmarks in SiSandra CPU benchmark and with PCMark04.
Coops
When Windows XP is installed, it checks your motherboard to see what type of HAL (Hardware Abstraction Layer) should be used. With some hardware combinations and BIOSes (I am still researching this), Windows XP, using its own judgement, might select an inappropriate HAL. Once the HAL is set, it cannot be changed without a new or upgrade installation of Windows XP. To check the HAL you have go to Start|Control Panel|System|Hardware|Device Manager|Computer. There are several HAL's available for windows to use and if it picks the wrong one, you will lose functionality. For example, my problem was that I was obliviously using the "MPC uniprocessor" HAL which disables hyperthreading. So even though HTT was enabled in BIOS, Windows did not recognize, or use two CPUs. (Task manager showed one CPU graph.)
There is a way to force Windows to use the HAL you want. During any installation (new or upgrade), when setup asks you to hit F6 to install SATA drivers, hit F5 (if you have a SATA drive hit both F5 and F6). The F5 key prompts you to choose a HAL. Use the arrow keys to navigate the list. For my case I picked "ACPI multiprocessor PC". Next, Windows will ask for the floppy with your SATA driver and installation proceeds normally. Afterwards, don't forget to reinstall chipset, LAN, sound and video drivers and windows updates.
With hyperthreading enabled I see up to a 33% increase in CPU benchmarks in SiSandra CPU benchmark and with PCMark04.
Coops
