My computer starts for half a second (CPU and case fans start spinning) and then stop. I have removed all connections and extracted the motherboard with the same results with solely the CPU, CPU fan, and memory. I used a second power supply, same problem. I purchased a new motherboard, same problem. I removed/switched the memory, same problem. I started without the CPU fan plugged in, same problem. I removed the CMOS battery for an evening, same problem. The only common denominator is the CPU. Is the CPU a possible culprit.
Motherboard: ASUS P5Q-E and P5G41-M LE/CSM
CPU: Core 2 Quad
Memory: DDR2 1066