i7 970 - Missing cores?

Just over a year ago I built a rig using an Asus P6X58D-E motherboard and i7 970 (Gulftown) processor with W7-64 bit Installed. Hyper threading all enabled such that back then task manager showed 12 threads as expected and CoreTemp reported and showed temps for 6 cores. Now however I only seem to have 3 cores! Task manager shows only 6 threads and CoreTemp only detects 3 cores. Windows msconfig is set to use all cpus and bios settings hadn't been changed. I have flashed to the latest BIOS (0701) but that hasn't changed the situation.

Any ideas what could cause this?

AFAIK you can disable cores in the BIOS, check to see if some are off or if there is any sort of power gating feature that might be getting in the way.

Check the bottom of the case, they might have fallen out.

Checked in the BIOS and it is set to ALL cores - tried setting to 5 but CoreTemp still reports 3 cores and task manager still only shows 6 threads. Can't see any power settings that would cause this and there weren't any issues when originally built.

adi - thanks for the suggestion, broke out the microsocope and searched the bottom of the case, but no luck I'm afraid!

Anyone got any other ideas?

Possible bios issue? I would first try clearing the CMOS, and possibly re-flashing the bios.

OK solved this. Was further confused by device manager correctly reporting 12 CPUs so disagreeing with task manager and CoreTemp,.

Going to msconfig->Boot->Advanced Options there is a checkbox for 'number of processors' which was set to 6. Unticking the checkbox and rebooting fixes the issue and task manager shows 12 cpu threads and CoreTemp shows temps for 6 cores. Curious as I'd never ticked this checkbox!

It seems that this is windows issue, you should go back to msconfig>boot>advanced options> uncheck number of processors option than reboot.

/lol sry we got the same idea in same time