If I turn off Hyper Threading, will XP ask me to reinstall/reactiv

[kovster]

I am wondering if it is bad for my system if I do turn it off in BIOS. I am
running a P4 3 GHZ with Win XP SP2.

I want to disable Hyper Threading in BIOS, but I am worried that it might
stuff up my system if I disable it (It was disabled by default).

I've got some process affinity settings already in place on some of my
programs (I.e. 'avast.exe' automatically runs at a CPU priority of
abovenormal), and I am wondering if anything will go funny once I have turned
HT off. I need to turn it off in order to play older Windows games, which
don't support HT.

Also, will XP ask me to reactivate/reinstall since it now only detects one
CPU instead of 2?

I can't remember if I actually installed XP with HT on or not.

One other thing: Is HT even worth having on at all anyway?

Cheers

 

[John John (MVP)]

You won't need to reactivate if you disable Hyper-Threading, you can
enable and disable HT at will and it won't make any difference to the
Windows installation, it will keep on working one way or the other. As
for your applications it should not prevent them from operating, most of
the applications should detect the HT status and adjust accordingly but
it is impossible to say for sure how they will react, you may have to
change some settings in some applications.

As to whether or not HT is worth it that is debatable to a certain
extent, many users will have a slight improvement in performance but it
really depends on what you do with your computer. With some
applications there can be some performance issue with processor cache
usage when HT is enabled. It is up to you to do your research and to do
some trials to see how things work for you, you can start here to get an
idea of the pros & cons of HT:

Exploring Hyper-Threading Performance - Technical Details
http://www.2cpu.com/articles/42_2.html

Some applications, especially older ones, may not be be well suited for
HT processors, they may hog all the processor cache and cause an overall
performance decrease:

Hyper-Threading Technology and Write Combining Store Buffers --
Understanding, Detecting and Correcting Performance Issues
http://www.intel.com/cd/ids/developer/asmo-na/eng/dc/pentium4/hyperthreading/20465.htm?page=1

John