when i format the pc 4 cores appears and are working ! after some time then become 2 !! i have an Msi 770 c35 mobo

Help , if it was drivers then how come it works for 5 days then this happens ?

here's what CPU-z shows
http://valid.canardpc.com/show_oc.php?id=909708

Ive used the MSI 770 C45 , It as ACC/Core control.
Try running MSI Live update for bios update

It looks like it is running ACC @ 2 cores. You dont need it so disable it anyways.

If you have AOD setup. Makesure ACC is set to either of or Auto.

-------------------------
Main Comp - Vista64 + XP .Phenom II B50x3 @ 3.300 24/7 MSI785GTM-E45.
2GB KhyperX 1066 Dual,
1TB Seagate 1x500GB Hitachi deskstar sata,
XFX 4850 HD/ 1GB @ 625-600
AOC 32" LCD

Comp 2 - Athlon 5200+ @ 2700, Asus M3N78-CM,
2GB Hyper X, 250GB seagate baracuda.
MSI 4650 1GB
Hanng 19" LCD

If that's a 770 chipset, ACC should not be an option with that MSI board.
ACC is only available with the 785 & 790 chipsets.
Make sure you update your bios to the most recent version that supports the 955.

-------------------------
Phenom II X6 1100T B.E.@ 4.26GHz
Corsair H70 Core Hydro
ASUS Crosshair V Formula
2x4GB G.Skill RipjawsX@ 1894MHz, 9-10-9-28
SLI: 2x EVGA GTX 570's@ 902/1804/2032
Creative SB X-Fi Xtreme Gamer
Corsair HX850W Modular
Cooler Master HAF 922
2x Win 7 Home Premium (x64)