Ram or Motherbord dead?

Ok I have a new 2600+ amd xp chip 512 ddr 333ram g-force 4 card I have had this system about 2 1/2 months. I booted up to windows xp as usal left the computer on for about 10 min came back to it opend a program and bam the screen goes black monitor clicks off power button doesnt work I have to turn it off from the back restarted the computer all the lights and fans came on but it doesnt make it to bios doest read vid card monitor doesnt even blink on I always monitored my systems heat the chip was at norm 52 degrees and at max 57 degrees C I tried reseting the bios check all connections resocked the ram nothing the system ran great b4 then any ideas?