I have a strange problem with my desktop PC. I tried different things to fix it with mixed success.

When I turn it on, it displays the BIOS/motherboard logo and then restarts. I can’t access the BIOS to edit settings because it restarts too fast. (I tried to reset the BIOS without success.)

I noticed that a capacitor from the graphics card was broken (it looked exploded) so I ordered a new graphics card and plugged it in. That didn’t help and it still reboots.

I tried removing everything that’s not necessary. I put a single one 1GB stick of RAM in the motherboard (usually it has four) and the computer actually started successfully (i.e., booting Windows). I then put in another stick of RAM and the computer still worked.

When I put in the 3rd stick of RAM, it didn’t boot anymore (again restarting all the time). I removed this 3rd stick and this is where it gets weird. I expected the computer to boot again because it is exactly the same configuration as before—which worked—but it *didn’t* work anymore! Now it is restarting even though it *used* to work.

The next test was to put a single of stick of RAM in the motherboard. It worked again and Windows would boot. I tried each stick of RAM in each of the slots, and it worked every time, so all of the RAM and all of the slots appear to be okay. It only seems to stop working if there are three or more sticks installed at the same time.

Further, the CPU fan is quiet when the system works and is loud when it does not.

Anyone an idea what might be wrong?