Prob with computer with Abit AB9 Pro motherboard

[christiani]

Hi everyone.
I've been having problems with my computer for a few months now, but it seems to have got worse in the last couple of weeks.
I have a (self built) pc with the following setup:

Abit AB9 Pro motherboard
Crucial Ballistix PC-6400 DDR2 memory (2 x 512mb sticks)
Palit 512mb DDR2/DDR3 graphics card
Hiper 430w PSU
Core 2 Duo e6400 processor
Cheapo Sony DVD-RAM drive
300gb Western Digital hard drive

At the moment it'll either turn on and boot up as normal, or as soon as it's turned on, start producing a long beep, which stops for a second and then starts again. The motherboard also shows the error code 'C1' on it's LED screen, which is an error relating to the memory. My initial thought was that there was a problem with the memory, but having had this replaced by Crucial, I have now rules that out. I'm stuck, and don't really want to send my motherboard back (the next thing I was thinkning of replacing), so wondered if anyone here knows what it might be.
Any suggestions would be much appreciated.

[BUFF]

have you got the memory voltage set properly according to Crucial's spec.?

[christiani]

Yes I have. It's set to 2.2v. I've also flashed the motherboard's bios with the latest firmware.