GA-EX58-UD3R Core i7 920 only 2 cores working

[Ericthefish]

I've just realised that only 2 of the 4 cores on my i7 920 are working, even though 'All' cores are enabled in the BIOS.

Windows Device Manager can see all 4 (actually 8 with Hyperthreading) but CPU-Z and CoreTemp both show only 2.

When I first built this PC back in October, all 4 cores were working fine, but I think I updated the BIOS at the end of November and wonder if that might be the cause?

I've tried using MsConfig to enable 4 cores in the Boot options but no success.

Any ideas how I can fix this please, anyone?

Case: Antec P183
Motherboard: GA-EX58-UD3R
CPU: Intel Core i7 920 D0 stepping
RAM: 6Gb Corsair XMS3 DDR3 PC3-12800
HDD: 2x1Tb Samsung Spinpoint HDD RAID 0 and 1x1Tb Samsung Spinpoint
Graphics Card: Palit GeForce GTX 275
PSU: Be Quiet! Dark Power Pro 650W
Heatsink/fan: Titan Fenrir TTC NK85TZ
O/S: Windows 7 64 bit

[Pottypete]

hi
you got the latest cpuz and core temp editions?
If device manager sees all 4 its ok
I think win disables cores for power savings and enables them as the needed
Cheers

[Ericthefish]

Thanks for the suggestion but I do have the latest editions (CPU-Z 1.5.3.3 and Core Temp 0.99.5). I'm sure they both showed all 4 cores before.

Win 7 does 'park' cores when they're not needed, as you say, to save power. Resource Manager shows 4 cores (should show 8, with hyperthreading), 2 of which are often 'parked'.

Any other ideas, please?

[Pottypete]

Hi,
don't have that mobo myself but is there a HT setting in the bios,
cheers

[Ericthefish]

Yes and its enabled.

[Pottypete]

Hi,
If you roll back to your previous bios does it show 4 cores + 8 with HT enabled!
Is there a bug in the new updated bios
Have you searched on the win7 64 bit forums @microsoft,
Maybe a win 7 problem not a hardware one!
cheers

[Ericthefish]

Thanks for the suggestion. I'll give it a try.

Is it normal for a later bios to cause problems like this?

[Ericthefish]

Found the solution!

Nothing to do with the BIOS;the problem was in Windows 7. The MsConfig boot setting caused the problem. Forcing it to use just 4 cores prevented it from using half of the 8 cores created by hyperthreading, effectively disabling two of the physical cores.

Thanks to Pottypete for the suggestion.

[Pottypete]

Hi,
Happy you got it sorted m8,
Made me chuckle about the old joke, "Drag N Drop"
One for solutions file,
Cheers

[oggmonster]

Ah yeah this seems to be a known problem in Win7 for some reason :/