Enabling Hyperthreading in Windows XP
:: Saturday, May 28th, 2005 @ 4:29:38 am
:: Tags: Computers
BEWARE: If you have a Hyperthreading processor and order a Dell with Windows XP Home installed on it, by default Hyperthreading will be turned off in the motherboard’s BIOS. This sort of makes sense because Windows XP Home supports HT, but not multi-processing. (continue reading if you’re a huge geek)
So the point is that if you then upgrade that machine to Windows XP Professional, you will have to re-enable Hyperthreading in the BIOS before you do the system install. And if you don’t, here’s what happens:
1) you use you machine for 8 months with HT turned off, while using — daily — applications that happily support multiple CPUs, during which time you wonder why only one CPU is showing up in your CPU Usage History graph in the task manager.
2) you stumble upon mindfulmusings.net, where the Mark Ghosh has has posted a quick 5-minute fix that will re-enable hyperthreading on your machine.
3) you smack yourself in the forehead repeatedly.
4) you sigh with resignation, because you know that your Mac friends will be making fun of you in the morning.
Helpful hints:
1) After you follow Mark’s three steps, you have to reboot. During the reboot, be sure to go into the BIOS and enable Hyperthreading.
2) I found ntkrnlmp.exe in my driver cache, in my Windows folder (do a search on your machine).
3) You can download halmacpi.dll here.
— Mark’s Steps, reproduced here in case his site ever goes down —
1) Download and install Windows XP Service Pack 2
2) Find the following files (normally in your c:windowsservicepackfiles)
- ntkrnlmp.exe
- halmacpi.dll
and copy them to your c:\windows\system32 folder. (This is considering your new motherboard has ACPI support. I know that these files will support non-ACPI computers as well, but that has not been tested)
3) Open up boot.ini in your text editor and find the following line:
multi(0)disk(0)rdisk(0)partition(1)WINDOWS=”Microsoft Windows XP Professional” /fastdetect /NoExecute=OptIn (or something of this sort)
and replace that line with:
multi(0)disk(0)rdisk(0)partition(1)WINDOWS=”XP Professional MP” /fastdetect /kernel=ntkrnlmp.exe /hal=halmacpi.dll
Make sure there are no line breaks in that line. (backup your boot.ini and your hardware profile if you want, that might be a good idea)
Now reboot, go through the installation and reboot of the new kernel and you are done. To test that you have SMP or hyperthreading enabled, hit ctrl-alt-del and task manager to see two seperate graphs for the processors.
>>> Full Text on Mindful Musings <<<
Journal RSS 
this is absolutely unrelated, but I think this is your cup of tea:
http://www.apple.com/trailers/....._blue.html
Did you notice much of a performance difference after enabling HT? BTW, I’m leaning towards the fancy Mt Hagen trip…
ha ha!
- one of your mac friends
Thanks for the tip! I turned on HT on my Media Center PC, (Dell 8300) on first reboot the tuner didn’t work but on the second reboot everything is working fine. I’m not sure I see as much of a speed improvement as when I bumped the memory from 1GB to 2GB but every little bit helps!
Whew, sure glad I’m a Mac user. :) Next purchase for home media: mac mini.
tribute to mac users - this is probably a little dated but is VERY funny ;-) http://members.cox.net/clyqz/mac.swf
I did all moving files and changing the boot.ine file and restarted and realized that I have an older processor that doesn’t support hyperthreading, haha. Luckily I had made a backup of the boot.ini file. Thanks for the tip anyway.
[...] Помощь была найдена где-то там. Technorati tags: hardware, software, windows  [...]
lol, probably a little late, but i was having diffuculty getting this to work on XP Home edition. it has HTT available, but disabled, as says 3dmark06, but this fix just aint cracking it.
i use a celeron d 3.06 with a 512kb l2 cache processor on xp home with sp2.
Also, IS THERE ANY WAY TO GET THE FUCKER TO RETURN TO NORMAL AFTER I FUCKED IT UP at all? like, if i use my backed up version of boot.ini, it just restarts when booting.
HELP IF ANYONE STILL READS THIS - agentsmithak@yahoo.com.au - cmon!
I have a hyperthreading system since 2 years now, so I can talk by experience. For lots of people it wouldn’t make any difference. It won”t make you type faster or fly faster through Google Earth, it doesn’t make your Internet connection any faster and fortunately it doesn’t make music or DVD movies run any faster either. Searching files on harddisk takes harddisk time, not processor power. And lots of programs, even Google Sketchup!! can only use a single processor.
But: I can run a file search on a 500GB disk, perform a large unzip, run disk defragmentation, a backup program and a 3D ray tracer all in the background simultaneously while watching a stutter-free movie. BTW both my disk defragmenter and ray tracer are HT aware, the rest of the software is not. In such cases CPU load is constantly near 100%.
[...] and you’re running multi-core-aware apps. And forget Windows XP. Most likely it’ll just get confused by all those CPUs or your license just won’t permit using them. You’ll need a hotfix and a prayer [...]