ASUS P4C800 Delux propblem with SATA Hard drive

i have asus p4c800 delux mobo and i am using WD 250gb Sata hard drive, all was working fine since few day it started to give me strange problem

when i shutdown my pc and restart the pc, it starts for few secs and when it initilaises the Hard disk it goes off again, i have to remove the power cable and insert again and have to do this several time and finaly my PC can boot and gives an error "cpu overclocking failed" but the pc starts normal after this error.

since 2 days, it wont start at all, it starts for few secs. and when it accesses HDD to initialise it, it goes off suddenly.

But if i remove my SATA HDD, everything goes fine, it works fine with IDE hard drives

What could be the problem and what is the solution ? i have allready falshed my BIOS to newest firmware.