I have a system that was a single core that I just upgraded to a dual core CPU. I seam to remember reading somewhere that there is there something I need to do to Windows XP pro to turn on the dual core/cpu support if it was originally installed on a single CPU (Reg Hack). I could just do a reinstall of Windows so it gets detected from the get go, but I really don't want to if I can avoid it. anybody know the trick ? Thanks in advance.

It will recognize 2 cores from the start I think, if not I think there is a little mod thing that utilizes both cores better if you keep searching around.

It should not be a problem since windows will properly setup to utilize both cores.

i remember under NT, it was a bitch to go from single to multi core. I forget the process but it was hell. There is a whole seperate kernel that windows needs to do this and switching them was like heart surgery if I knew what that was like. Windows 2000 had this problem as well I think.

Havent tried it in XP yet though, but I would put it against a reinstall of the OS... It is the ONLY way to insure full dual core success though (with optimizations).

I couldn't remember, if it was a quick reg hack or something major. I read something on it a long time ago and it was on all NT based OS's. I haven't heard much on the topic in a while either and I'm surprised because multi core cpus are such the norm now, where three years ago it was only a select few and mainly servers that had them. If it looks to be the best road I guess I will just do a reinstall. Anyone else have some insight on this.

Technicaly when you put in the new CPU it will find the 2nd processor (or core in this case) but that doesn't meen that the system will be using both processors. The easy way to check is to bring up Task Manager and choose the performance tab and see if you see two graphs one for each core. Most likely your only going to see one. If that is the case you are going to have to replace the hal.dll and ntoskrnl.exe from the single core version to the multi core version.

You can do this two ways.
Option #1 - Hal / NToskrnl replacement
a. Make a directory called DUO on C:\
b. Copy halmacpi.dll (search your C:\ drive for this) to C:\DUO then rename it to hal.dll
c. Copy ntkrnlmp.exe (search your C:\ drive for this) to C:\DUO then rename it to ntoskrnl.exe
d. Make a batch file called go2core.cmd and put this in the file.


C:
CD\windows\system32
REN hal.dll hal.old
copy C:\Duo\hal.dll C:\windows\system32
REN ntoskrnl.exe ntoskrnl.old
copy C:\Duo\ntoskrnl.exe c:\windows\system32

e. Run Go2Core.cmd from C:\duo directory.
f. Reboot and you should now see two processors in Task manager

Option #2. Add a 2nd boot option to your boot.ini file
a. Copy halmacpi.dll (search your C:\ drive for this) to C:\Windows\system32
b. Copy ntkrnlmp.exe(search your C:\ drive for this) to C:\Windows\system32
c: Remove the read only flag from c:\boot.ini (right click on file and remove check box)
d. Edit your boot.ini file to the following

#ORIGINAL boot.ini

[boot loader]
timeout=30
default=multi(0)disk(0)rdisk(0)partition(1)\WINDOWS
[operating systems]
multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="Microsoft Windows XP Professional" /noexecute=optin /fastdetect


#EDITED boot.ini

[boot loader]
timeout=30
default=multi(0)disk(0)rdisk(0)partition(1)\WINDOWS
[operating systems]
multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="Microsoft Windows XP Professional" /noexecute=optin /fastdetect
multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="Microsoft Windows XP Professional Multi-Processor" /noexecute=optin /fastdetect /HAL=halmacpi.dll /kernel=ntkrnlmp.exe


Now if your Windows install is NOT on the first partition then you might see a different partition number in the boot.ini so whatever is in your boot.ini keep it the same.

Now when you reboot you should see two options and you have 30 seconds to decide which version you want to load.

Microsoft Windows XP Professional
or
Microsoft Windows XP Professional Multi-Processor




Now... If you don't know what your doing.. Please don't blow up your laptop and blame it on me. I have a vast background in a multitude of OS's and have been in the IT field for years.

I do not take any responsibility if you break your laptop.

Other then that... I will answer any other questions you might have

ditto.




i need to get these Van Wilder one-liners out of my head! Write that down.

let's see.... think other thoughts.. how 'bout:

I whacked a Mac.
A Mac I whacked.
And on that whacked up Mac, I

I thought it was as simple as uninstalling the old processor from device mangler, rebooting, and installing the new processor???

That does not replace the Kernel and the hal (Hardware abstraction layer).

How about forcing to a single core from msconfig>boot.ini>advanced options>/numproc=1. Then reboot, change it to /numproc=2 then reboot again. Won't windows know to make the needed changes to compensate for the dual core. Or is the /numproc option greyed out as it's only seeing a single core in the first place?

/numproc is only used when you have a multi-processor HAL and Kernel installed. It is a switch developers use for testing applications on a single processor.

Errrr - instead of doing open heart surgery on the OS, how about doing a repair installation of Windows XP instead?

http://support.microsoft.com/kb/315341/

Why re-invent the wheel. Replace the HAL and KERNEL.

Done and Done..... It's a 30 second job unlike re-install or repair which could really hose things up.

We have used the .CMD file I made on over 100 machines. Since we have a single image for all our Desktops based on the Single core Optiplex machines I made this script to run after ghosting on the newer duel core machines to enable both processors.

It works trust me.

I won't bother with the whole spiel about how he's running a laptop and you're doing that to desktops (which are most likely standardized).

The main point is while you can change the files, there are settings in the registry that don't get changed (if I remember correctly) when you just do something like that. A full driver install will ensure things are properly installed.