My PC won't boot...


On Sunday morning I tried to start my home-built computer. However, when I pushed the power on button on the front of the case, absolutely nothing happened. No beeps, no fans, no output from the GPU, nothing. So, immediately I thought a fuse or something had blown, and the PSU wasn't getting power. Upon inspection I found the red light at the back of the PSU on (there is a light inside the PSU's power on switch). I switched the power socket anyway and tried again without success.

The PC shutdown absolutely fine on Saturday night without any hints of a problem, and after light use. I built the PC myself a year and half ago and have had no substantial problems since then. Here are the specs;

AMD Phenom II x4 965 CPU (Black Edition)
Gigabyte MA770T-UD3 Motherboard
ATI Radeon HD 5750 GPU
Hiper Type-R 580W PSU (modular)

All parts were bought new apart from the PSU which I bought second hand, the stcker on it says it passed quality control in Dec 2005, so it is quite old, but hasn't given any problems yet.

I have tried everything I can think of or do with the tools I have available (I don't have a spare PSU or voltmeter laying around to really test things). Nonetheless, I have tried a number of things. I tested the case's power button by both shorting the two terminals on the motherboard, and by switching the reset and power buttons (i.e. plugging the reset button into the motherboard's power on terminals), both to no avail. I checked the motherboard for leaking or burst capacitors, but I cannot see any and there are no unusual smells from inside the PC . I also couldn't see anywhere where the motherboard could be shorting out.

So I decided in anguish to completely strip and rebuild the PC (ruining many hours of cable management :( ). I took EVERYTHING out, and unplugged everything, the only thing I wasn't able to remove was the CPU and its heatsink since I had no thermal paste to put it back together . I put together the bare essentials ; the PSU , CPU, GPU, one stick of RAM, and ofcoarse the motherboard, along with the CPU fan and one case fan (both connected to fan terminals on the motherboard - I normally have 6 fans connected to an Akasa fan controller) . I tried again, but nothing happened, just like before. I then decided to rebuild an old Dell computer I had to get online to check for solutions (I have no other PC in the house). When I was reinstalling Windows on the Dell, I happened, out of boredom, to turn the PSU off and then on again via the PSU's switch on its back. I tried the power button again, and to my surprise the computer began to boot! It obviously didn't fully boot because I had no hard drive plugged and the BIOS displayed an error to that effect.

I thought that maybe there was a problem in the ATX power cable or GPU power cable (I have extensions for both), and as a result power wasn't getting to the essential components.

I figured whatever problem there was had sorted itself out, so I began rebuilding the PC (this time without the power cable extensions). However, I have not had the computer working since, neither when I had the computer partially rebuilt, nor when I restored the PC to the bare minimum that I had it at when it worked last (I took the computer apart again to that bare minimum when it wasn't working in the more built up state).

I should mention that the PSU does not have a voltage selector to differentiate between USA and UK voltages, so it cannot be that this was accidentally moved to the wrong setting. Also, the PC had power being supplied to it the whole time I was preparing the old Dell (around an hour or so) before I had it working in the bare minimum state.

I am obviously very confused. I figure there must be a problem in either the PSU or the motherboard, but there is the red light on the PSU when it recieves power indicating it is ok, and there is no visible damage (that I can spot) to the motherboard, and it booted in the bare minimum state, which suggests the motherboard is fine.

Obviously, any help in discovering the problem would be much appreciated .

Ryan Mckeown
8 answers Last reply
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  1. Have you tried starting the PSU completely removed from the system? With the power switch in the ON position, shorting the green and any black wire in the 24 pin connector should start the PSU. If it doesn't do that every time, the PSU is faulty.

    Next, you would need to check voltages at the various circuits. Since you have no testing equipment, you may want to purchase an inexpensive PSU tesrer like one of these:
  2. Just short the pins on the motherboard with a key or something, less risky!

    There is a chance it could just be the button itself!

    Edit: sorry missed out the middle paragraph should have read more carefully. Yea your going to have to test the PSU the way clutchc said, just be careful..... read a post the other day where someone had done that and accidentally touched the blue wire and blew the whole PSU
  3. Thanks guys for the responses.

    I took the PSU out this morning and tried shorting the green and black wires on the 24 pin connector using a bent paperclip, as advised. I tried turning the PSU on like this about 10 times, all without success (the fans never started up in the PSU).

    So I guess this indicates a PSU failure? If so, I remember having trouble deciding on a suitable PSU last time, so can anyone give me any recommendations. I have heard Seasonics tend to be good. I am planning a few upgrades, so I need a PSU with a little more power, at least 700+ Watts. Also, I would also want one that runs quiet, is reliable, and preferably costs less than 100 pounds (GBP), although I would be willing to go slightly over budget for a VERY highly recommended PSU.

    Thanks again,
    Ryan Mckeown
  4. machione said:
    Thanks guys for the responses.

    I took the PSU out this morning and tried shorting the green and black wires on the 24 pin connector using a bent paperclip, as advised. I tried turning the PSU on like this about 10 times, all without success (the fans never started up in the PSU).

    So I guess this indicates a PSU failure?

    Yes, you pretty much proved out that the PSU is at fault. If a new PSU doesn't solve your situation (it should), it may be because the PSU damaged something else when it failed. But that's not all that likely. If you want a good review of which PSUs are quality and which are not, take a read at Jonny Guru's site:
    If you're just looking for a recommendation, I have always had good luck with XFX units. I have the 850W Black Edition, but I don't think it's made anymore.
  5. Thanks again guys for the responses.

    I decided to go for a Corsair AX 850 PSU. It was a little over budget but sure...

    Anyways, it should be here in a few days, so I will let you all know how it goes when I install it.

    Thanks again for everyone's help.

    -Ryan Mckeown
  6. Hi,

    PSU came today... success!!!

    Fitted fine, and computer is running like normal. Great job!

    Thanks to everyone who helped with the troubleshooting. Much appreciated.
  7. Glad to hear of your success. Enjoy!
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