Problem with reading drives

hi, 2 days ago my PC started crashing into blue/black screen with the warning "C: read error" or something like this.

i thought it was the HD, so i bought another HD and installed windows again.

now, installed, the C: and D: take too long to read then finally can't read, windows can't even start because the HDs is not detected in BIOS. i switch the C: and D: port to port 5 and 6 for SATA 6Gbps, they can read it.

but now it can boot, it still shows some problems, like the eSATA sometimes can't read, DVDROM (also SATA) can't read also sometimes.

i'm presuming the problem lies in the HD controller (motherboard, ASUS P8P67pro), but my friend told me he had the same problem and the problem lied in the PSU.

how can i make sure which one causes the problem?
my mobo is ASUS P8P67pro, just 2 months old, still guarantedd;
my PSU is corsair 520HX, about 3 years old. last time i checked the basic voltage from ASUS software, it's normal but now i can't install it since the DVDROM hardly reads anything.

A faulty power supply unit does seem to be the problem. Are you in a position to get it checked at your local repair shop?