I'm trying to diagnose what is wrong with my mother's computer. It is a Compaq that is approximately two years old. Several months ago she informed me that the computer would not power on and that there was a light blinking in the back (the power supply). So I had the power supply tested and it was fine. I eventually disconnected the floppy drive and it booted up with no problems. Now, after several months of use the same thing has happened again. The computer won't boot up and the light on the power supply is blinking again. The power supply is Bestec ATX 250-12D. If I unplug the 20 pin connector that connects to the motherboard the light on the power supply goes from blinking to constant. Does this mean I need a new motherboard?