I have an HP Pavillion Elite that will not boot. It starts for a few seconds then shuts off, and repeats this cycle. So far I have removed all the RAM and connections to the HD and the problem persisted. I noted that when I removed the power to the CPU it would stay powered on at least. So I tested the power supply with a multimeter to both the 24 pin motherboard connector and the 4 pin CPU power and both tested as the appropriate voltage.
I have just removed the CPU and the machine stays powered on. Does this mean for certain that the CPU is causing the machine to fail after a couple seconds and restart? I want to make sure that I buy the right component and at this point I can only think I have either a faulty CPU or motherboard.
do you have another system you could test it on (needs to be the same cpu socket)
you probably would see it displaying correct voltages because theres no load on it, try to get some draw off of it and test again