Hi, after tens of successful repairs, I am having a very serious problem with my PC. When I turn it on, nothing happens, except that the cpu fan start rotation and suddenly stops and that the power led on front stays on. No beep at all is heard. The power supply is ruled out because I tried it on another computer. Do you think it might be the motherboard? It is ASUS. Thanx.
Check if the CPU fan is wired directly to the PSU. . unless the motherboard is giving-back the right voltage signals the PSU will "shutdown"....so it could be the MB connector, since you say the PSU is itself OK. When things stop...life gets troublesome as these systems are inter-dependent, closed-loops. - The CPU "fan stopping" may indicate the PSU is being forced Off. The light merely shows there is power available...but I supect the MB is not taking the power hence the PSU shuts down very quickly.
Check the CPU heatsink installation. The symptoms described are pretty common when a motherboard is shutting down to prevent damage to the CPU because the temperature safety threshold is surpassed.
Big Al, you may be right, but I can't believe a system would also shut down the fan, if it was hot. - I understood the event from start-to-stop was a second or two...just enough to see the fan move - this needs clarification! For a processor-overheating to occur with an experienced builder, it would take minutes IMHO for the processor core to become extreme - even on a warm day and that's not the situation, or we'd be told. He's got the heatsink and a fan - hasn't he? (Maybe it's fixed, he's not come back.)
HI, I had the exact same problem in a system some days ago: the system used to start and after a few seconds the video signal was lost and, the CPU fan stopped and the HDD led stayed on. The problem was the Power Suppy, I changed it and every thing started running OK. You said you tried this PSU in another computer, I would recommend you to try another PSU in your system and disconnect all the unnecessary devices that may consume more power that the PSU is capable to provide. You may think in a MB connector failure too, as some friend told before. good luck
If changing the PSU eliminates the problem it is very easy to conclude that the PSU is "faulty" - but in this instance we are told the PSU works OK (with another PC.)....of course we don't know if that's a light load, but we have to make assumptions that the test was reasonably valid - and that means similar - So where does this leave us?Back with the originator IMHO - He suspected the Mbd but didn't say why - it was unfortunate he couldn't try the other PC's PSU - since that would more-or-less eliminate dirty connections, wiring etc. I have a fault (on this PC) which appears to be wiring-related and even with some experience in fault-locating it is not easy to identify faults that are, at best, "intermittent" - whereas in this scenario we are told that the fault persists. I suspect also that if the fault was a result of extra-load this builder would have discovered the reason themselves - but we are left without any such info. .. I think we need an Update - before we speculate too much further.
