My computer did this for a few days until I re-checked my GPU. It somehow became unseated, so I re-seated it and the problem went away. I have no idea how it became unseated, but it was.

I'm like 90% certain that's the PSU. Always possible it's a capacitor on the mobo or something, but it sounds far more likely that your power supply is overheating or just failing outright.

Considering which PSU it is that does indeed seem likely.

You don't have to test it at your place or even take it out, just unplugging everything and doing a paperclip test might be enough. If it fails that then we know it's the PSU for sure.

Thanks, I'll give that a shot. Any recommendations on good PSUs in case I need to buy a new one?

A good rule of thumb is finding anything with SeaSonic as an OEM. While they sell their own parts (which are always good values) sometimes you can find rebrands (like Antec or Corsair) that still use Seasonic internally, for cheaper.

Just go to this website, click the desired brand name at the top, and look at the listed OEM of each PSU model.

There are other good power supply OEMs besides SeaSonic but not all of them are universally good, and Seasonic is prolific enough and generally cheap enough that looking for them is an easy rule of thumb.

@Setsul if you know of any better PSU OEM databases I'd love to know. The Who's Who In Power Supplies articles haven't been updated for years, and while going for old models listed there isn't a big problem, there are plenty of new models with no easy information available, on top of the fact that OEMs sometimes change.

The funny thing about seasonic is the first time I went with a reasonably high end PSU it was a Seasonic and it was DOA. But thats just my bad luck. After I RMA'ed it its been solid for 3 years, and I'm now running in another computer a corsair 750W made by Seasonic.

I agree its most likely the PSU. Any other failure should trigger post codes and allow the machine to stay powered on longer than a few seconds. Computers don't like high humidity. It's funny some newer motherboards (like mine) have a dehumidifier feature in the BIOS which I believe just powers on the computer and fans, maybe puts the computer under a little bit of load or something to clear the humidity off the internal PC parts.

I still buy mostly seasonic OEM'ed power supplies. I have a couple other ones in other machines one is a PCP&C made by seasonic. If you check slickdeals sometimes you can find good units for as low as $25-30 after rebate for like an 80+ bronze seasonic made 400-500W.

#5
No idea about prices in India. Any shops / price comparision site?
Budget?

#6
OF course I do.
http://www.realhardtechx.com/index_archivos/PSUReviewDatabase.html
No platform information but ALL the reviews so you can generally figure it out with the pictures.
orionpsudb is fairly new so they don't have all PSUs listed yet, although they keep adding more brands, platforms and models. I'll still keep using realhardtechx for the rated wattage, cabling, rail information and review links, but not having to guess the platform anymore is nice.

#7
I think Corsair used to be skimping a bit on the QC to improve their margin. Works with Seasonic since >99.9% of the PSU will still work without any issues even if it was never tested but when they got too greedy and tried the same with CWT it was a disaster (RM series).

Ok, so I tried removing, cleaning and re-seating the GPU and it powered on and stayed on after that. Only problem is now the display refuses to turn on and the monitor immediately enters sleep mode, both with and without the GPU installed. No beeps, doesn't even reach the BIOS. Really hoping it's not a motherboard issue.

Any suggestions on what to try next? I don't want to send in the motherboard without actually being sure it's the issue.

Have you tried onboard graphics?

Paperclip test?

Tried onboard graphics earlier, but that didn't help. How would the paperclip test help now that it's actually staying on?

when i was building my new computer i had the same issue and it was my motherboard that was the issue. took me like 2 weeks to get a new one but when i got it, the computer worked fine so it may very well be your motherboard

#11
Would you mind telling us what you've already tried without us having to ask first?

Paperclip test because it did weird stuff before. Ideally you'd monitor the voltages and PWR_OK signal as well but I don't think you've got the test equipment necessary for that.

Well, like I said, on the 16th I reset the CMOS battery, checked the MOBO/CPU power connectors, re-seated the RAM(and tried one stick), shorted the power button pins on the motherboard with a screwdriver. Today I cleaned and re-seated the GPU, tried connecting the monitor to the GPU DVI port, and then to the motherboard DVI port(without GPU connected)

I'll try the paperclip test tomorrow or day after when I get a chance to go there.

That exact thing happened to me.

Lights and fan would work but nothing else.

I thought it was the PSU but after RMAing it, no change. It turned out to be the Mobo. This was when I first made my build though, but it's still worth checking the mobo.

Think I'll send the motherboard in after I check the PSU. Thanks for the help everyone

So an update. The day before I took the motherboard in nothing would come on, not even for a second, but when I checked the PSU separately the fan would start up. I took the mobo to the service center, they checked it, cleaned it, replaced some part of it and it booted and reached the BIOS with their PSU/CPU/RAM setup.

I brought it back, reseated the CPU, thoroughly cleaned the CPU fan, re-applied thermal paste, connected the CPU fan, one stick of RAM and booted. So it booted up(unlike before I took the mobo in) but only for 10 seconds(nothing on the display) before powering down and then and endless cycle of the same powering on and off. I re-checked the standoffs, checked all the cables again, moved the PSU out as far as the cables would allow me and cleaned it, and it finally booted, both with OS X and Windows. So then I put in the 2nd stick of RAM, put in the GPU and try again; once again, it boots both into OS X and Windows with no issue.
Finally, I re-connect the side panel fans(and may have potentially brushed some other cable with my hand), put the panel back, press the power button, and am just about to clean up, when I realise it's doing the 10 second endless boot cycle shit again. I rebooted after disconnecting all the case fans, and it still refuses to get out of the boot loop.

I'm really lost at this point. Should I take the PSU home and check it with my setup, or could it have anything to do with the cabinet fans?

Can't be the fans since the same thing happened even with them disconnected.

Test the PSU before trying anything else. I mean if it booted with their setup apart from the PSU it could only be the CPU or the RAM. Sure, you could test with your RAM or just whatever DDR3 you can find, but I still think it's the PSU.

Sorry for the late answer.

Thanks, I'll try to get the PSU to my house and connect it up here asap.

So, it's apparently not the PSU either. I brought it home, connected the CPU and 24-pin connectors to my board, and the PC immediately boots(into BIOS) and even stays on, whereas with my friend's PC it won't even start up any more.

I'm completely fucking stumped at this point.

Tried different RAM?

I'm not sure how much faith you have in the mobo repair.
Either the mobo is still having issues or it's the CPU.

Really late, I know, but I eventually gave up and dropped it at a repair shop. Turns out the motherboard, PSU and even the processor had problems. Luckily everything was under warranty and the repair place charges a very minimal service fee.