I have a Dimension 5100 that would constantly reboot itself. Thought it was the CPU overheating so I replaced the factory fan and added a second one.
Then all of the sudden the computer beeps at me 1-3-2, which is the memory being not recognized/not there. Also diagnostic lights 3 and 4 are on, which point in the same direction. I have used 3 different ram sticks, one that was in it and 2 brand new ones and tried them in each memory slot one by one with the same results.
I tried switching the CMOS battery to no avail.
I removed all internal cards and drives leaving only the onboard video, hard drive and memory in place.... yeah you guessed it, same problem.
I am thinking the motherboard is done for. Since the computer rebooted itself even in BIOS after random number of seconds or minutes.
Any thoughts would be greatly appreciated. If I could give a penny for your thoughts I would.