I am trying to put together a new machine, but the computer cycles on and off by itself every 3 seconds. The LEDs light up, PSU fan spins up and then all goes off. Up and down every 3 seconds or so.
At this point I've removed the motherboard from the case to make sure it's not shorting against it and have removed all components from it. Just plugging the PSU into it and using the onboard power switch and I still have the same problem. Tried two different power supplies. Tried resetting CMOS.
Should I expect an error beep if the only the PSU is connected to the mobo and all is well? Does it sound like a DOA board?
To get 'beeps', you need to plug in a case speaker here:
Your problem, however, most likely has to do with your fan/heatsink; does the fan on the CPU also spin up? If not, check that it's plugged into the correct header. Look at the back of your board, and verify that all four retaining pins for the heatsink are correctly and fully seated, and not cracked or broken. Did you look somewhare on the web to see how much compound to apply, and where? When fastening the pins, start with a pair of diagonally opposed pins, and then do the other two.
The symptom is thus: the CPU powers up and starts the POST sequencing, but can't successfully 'spill' heat to the HSF, and so goes immediately into thermal shutdown to protect itself...
At the moment I do not have anything other than the motherboard and the PSU connected. Thus only the PSU fan spins up.
Thank you for pointing out that case speaker is responsible for the beeps. I had completely forgotten that I did not have it connected to the motherboard because my case (Antec P183) did not come w/ a speaker connector with the front panel wires.
I only had a limited time to work on putting my machine together and did not get around to plugging all the components in. I had tried to power it on prior to installing RAM and the CPU just to see if all was well so far.
So my question is whether this is expected behavior for the motherboard to cycle without the CPU and CPU fan plugged in? I will have time to try finishing up the installation soon, but I was surprised that it would cycle w/ just the PSU plugged in. I have never had a board do that before and was wondering if I need to abort before I go through with the installation of the remaining components.