I came into a computer today and it was apsolutely filthy. It booted up ok, but it neeed a good cleaning. I took off the CPU fan and heat sink and cleaned it off and put it back exactly the way it was. I compressed air'd the rest of the dust and gunk on the inside and reconnected everything just like before. Now it starts, but nothing shows on the monitor, (the monitor light stays yellow instead of green) and I noticed a red LED2 light flashing on the motherboard. INTEL A-OPEN #AX4SG-N. I'm thinking overheating of the CPU? Maybe I need to clean off all the black that was on the back of the metal heat sink/CPU fan that was burned onto it from the CPU? Do I scrape it off and put some of that white gunk on it? Could some of the dust that was scattered around have landed on the CPU and be causing the problems? What the heck is a LED2 anyway?
Any help and ideas will be greatly appreciated.