Anyone know what could have caused this? Pc would power up, show this error and then shut down. No display or beeps etc. I tried a different graphics card to no avail. Some reading led me to try the MemOK button which made the pc boot, but needed to be used for each boot. I reset the bios to get rid of overclocking and now it boots fine. What could have changed to make it fail? It's been running fine for years. A few days ago it made a horrible noise like a fan was failing, but after a restart has been fine, until today.