Hyperthreading

[ADS_Tech]

.............we are with a different motherboard to the start of this thread now on a seperate PC. The first issue has been sorted by changing cpu.

[Radical Dreamer]

And am I right in thinking that in order to utilize hyperthreading properly, it must be enabled in the BIOS before installing the OS?

And also that it CAN be switched off in the BIOS afterwards, but then not switched on again without it creating issues.

You are 100% correct, I've not seen many people have much luck with turning HT on and off, if you have changed the CPU then you should reload the OS or you will have some weird issues.

So in short, if its off when you install, leave it off, if its on when you did the install leave it on

[tyamada]

BTW
I have two processors showing in device manager, but only one in Task Man.

When only one processor is showing in the task manager, means HT is not working properly. I had the same problem on my Asus P4C800E-Deluxe. Fixed it by uninstalling both processors in the device manager and rebooting the computer.

Had a friend that upgraded to a HT mother board and was not able to get HT to work proplery. He had to a clean install. If you just move HDD to a new motherboard HT may not be available.

[Yak144]

Im having the same problem as tyamada has had. I have a P4CF800 Deluxe motherboard, and i just bought a 2.8 GHz processor w/ HT, but still only one cpu showing in task manager. I also tried uninstalling the two cpu's in the device manager and restarting, but that did not work.

Are there any suggestions as to what i should do?

[Carpel]

I put a machine together that w/ a 3.2 P4, and Radeon A-I-W Pro. I ran into an issue with HT that caused the machine to freeze whenever the tv app was running.

ATI's support site pointed to a fix # at M$, and stated it will be included in the next service pack (SP2).

M$ is was reluctant to distribute the fix as it was still in beta stage. I found it online and installed it, however it didn't totally resolve the issue until the next A-I-W drivers came out.

So I know there are some instances when HT will cause issues.

But I'm not givin up my HT either !

Carpel

[format c:]

No problem turning off Hyperthreading on my Asus P4C800 delux, All because of one of my programs crashing on me
Do many games support hyperthreading ?
I may just turn it back on, When hyperthreading is enabled you will see two cpus under device manager and taskmonitor
Time to back her up

[NooNoo]

Im having the same problem as tyamada has had. I have a P4CF800 Deluxe motherboard, and i just bought a 2.8 GHz processor w/ HT, but still only one cpu showing in task manager. I also tried uninstalling the two cpu's in the device manager and restarting, but that did not work.

Are there any suggestions as to what i should do?

Welcome to Windrivers Yak144

If the os was installed before you upgraded the processor, you should reinstall windows - preferably a clean install, although you can try an install over the top to see if it sorts it.

Are you running 2k or XP? Either way, the latest service pack and the other critical updates will need to be reapplied.

I think the problem is due to the fact that processors where not designed to be plug and play

[CrazyArian]

I have 2 machines that have HT and under the processor settings is a HT enable or disable. Sure it should auto detect if there is HT or not but I haven't seen where you couldn't turn it off.

[Thag]

When you install the OS it looks to see if you have one processor or multiple processors and it sees HT as a separate processor. Depending on which one it sees, it installs a different HAL (Hardware Abstraction Layer) - basically the translator that lies between the hardware and the software.

To see which is installed look in Device Manager, under Computer - it will either say "ACPI Uniprocessor PC" or "ACPI Multiprocessor PC".

I saw an article in the MS KB once for how to upgrade from single processor to SMP (symmetric multiprocessing). As I recall it was fairly involved and not for the faint of heart. And, of course, not recommended by MS. I will try to find it again and post it here.

[Thag]

Here's one about trying to go multiprocessor to single processor. Basically it says reinstall the OS.

http://support.microsoft.com/default...b;en-us;811366

[Thag]

Hmmm. This one says you can go single to multi by changing the HAL in Device Manager. Very interesting . . . .

http://support.microsoft.com/default...b;en-us;246236

[Thag]

Slightly more info here . . .

http://support.microsoft.com/default...b;en-us;309283

[Budster64]

unfortunately there's no info on the Asus site to indicate that this particular model even supports hyperthreading. Nor can I find any info on the web concerning this model and HT.

Usually task manager does show 2 CPU's unless you have your view set to 1 graph for both CPUs or it's not functioning properly.

Using WXP and an Intel 865PERL I was able to enable/disable HT at will through the BIOS without any repercussions whatsoever. This may be an isolated incident and certainly I had problems doing this with W2K wherein I had to change the HAL. That's not always a pretty thing.

You can't disable HT through the registry nor through the OS as this is enabled/disabled at the BIOS and only there can you change it.

In lieu of a complete re-install you can always try doing a repair of the OS by booting to a WXP CD (if in fact the OS is XP, not sure if you mentioned it) letting it detect the OS present in the partition and electing to repair the installation instead of over-writing it. This should delete the old HAL and install the correct one.