Can't install x64 after upgrading to quad core?

The only variable here is the switch from the dual core e6600 to the quad core Q9400. I've been running osx along with various versions of windows inclulding xp, vista, and win7 7000 x64, 7057 x64, and 7068 x64. They are on separate hard drives, and osx loads using pc-efi v9 which is only installed on the osx drive. No changes or hacks are made to the bios. I don't use any 3rd party boot managers, i simply choose which os to boot by selecting the primary drive from the BIOS boot selection screen. I can and have removed the os x drive from the system and it is then exactly the same as any other pc.

I only mention the fact that i have os x installed because because it is also a 64-bit OS and is running as usual after switching processors, which would seem to rule out an actual problem with one of the CPU cores. (possibly leading to the OS thinking there was some sort of multiprocessor mismatch going on...)

edit: i did reset my bios to defaults when i upgraded the processor, so it's possible there is a setting that i have adjusted differently than before when everything was working...

found a report from another user with the same issue, same motherboard -

MULTIPROCESSOR_CONFIGURATION_NOT_SUPPORTED error while trying to install Windows 7 64bits

Same BIOS version as me. Now i am trying to remember if the last time i was using win7 was before or after i updated to the latest BIOS revision...

Sorry for the multitude of posts, but i've found the solution.

There appears to be an incompatibility with the latest BIOS for my board. I had updated to this BIOS in anticipation of swapping CPU's but had not attempted to boot windows 7 until after the new CPU was in, so i don't know if the problem would have also shown itself with the dual-core CPU.

Rolling back to previously released BIOS version fixes the problem. Unfortunately for me, that previous BIOS also does not properly recognize the Q9400, it just shows up as "intel cpu". I'll have to see if that causes any issues...

chris3g said:

i did find one report of the same problem when searching, here - Windows 7 Installation not compatible with multi-core processors!?

no resolution though

This must be total B/S as W7 works fine on QUAD processor - no probs

Cheers
jimbo

Please provide the output of "reg query HKEY_LOCAL_MACHINE\HARDWARE\DESCRIPTION\System\CentralProcessor\ /s" from the affected system.

Thanks,
JohnE [MS]

What is really needed is the output of CPUID 0x1 for each processor. Tools like CPU-Z can dump this from the 'About' tab by clicking 'Register Dump'. I don't know what would be comparable on osx86