Memory channel A does not boot

[Guest]

Hello,
my D875PBZ motherboard with intel Prescott 3.2 Ghz stopped seing any memory in channel A (so 2 slots are useless and dual channel operation impossible). When I place memory there, the cdrom light blinks and system does not boot. What could have caused that, how to solve it?

 

[r_manic]

You said it stopped seeing it, so everything was running smoothly before? What are the other specs of your computer, I'm suspecting that either your mobo is faulty or there's something wrong with the PSU.