I'd start from scratch, disassemble and reassemble, disconnect everything but memory and cpu, reseat both cpu and memory and hope it boots, if your sure psu is fine, could be a bad board, also try vga and dvi connectors unless you already have....thats all i can offer to tell ya, good luck.
thats an odd error to get since your tryin to boot with onboard video, thats why i suggested reset bios...remove any other cards you may have in there.