PC powers off ocassionally

[marek.mikes]

Hi,
I have a new PC for about 3 months and it went to a state when I couldn't turn it on for a couple of times now.
That means no matter how much i pushed the power button or tried to switch the power source on and of, the computer would appear completely dead. After some time, if would turn on (fans start spinning) but shut down after a few seconds. In the end, it would turn on, but I have no idea why. Last time it happened, there was a problem with BIOS being corrupt, then after it refereshed from the backup, I still had to reinstall Windows, since the computer wouldn't turn on. I first suspected, it happened after sleep mode, but today, the computer powered off while i was working with Word, for no apparent reason.
There was also no BSOD, just the PC going dead all of a sudden, and I can't really find any logs of what happened (no minidump or anything). This time, the computer powered on after I unplugged and pluged what i believe is the power cables of the motherboard (there were 2x4 thin cables) also with some BIOS problem, but this time I didn't have to reinstall.
I was thinking there might be a problem with the power source, since the PC seems all dead, but I really don't know how to make sure. Now the PC runs fine.
I'm using win 8.1, seasonic 500w energy knight source, GIGABYTE GA-B75-D3V motherboard.

[rubberman]

You have a hardware failure. Remove the disc drives and send it in for repair. If you send it in with the drives, they will probably reformat them, unless you specifically tell them not to, but that is no guarantee that they won't...

[mike_2000_17]

seasonic 500w energy knight source

This seems like a very weak power-supply for a relatively new computer. I had a relatively new computer about 3 years ago with a 550W power-supply, and it ended up breaking because it was under-powered, and so, replaced it with a 850W power-supply and has been running smoothly since. And your description sounds a little bit like a power-supply problem, although the bios corruption stuff is a bit weird. In any case, I don't think that a relatively new computer could possibly run well on a 500W power-supply, that's just too weak. It is very common for computer stores or suppliers to package weak and obsolete power-supplies into their products because customers often don't pay much attention to that component, so they can pass off cheap, obsolete or under-rated power-supplies easily to unsuspecting customers. So, I would definitely try to get that power-supply upgraded.

Beyond that, it is hard to tell exactly what the error is. If there seems to be some bios error, then you might want to try a factory reset of the bios, which is a very simple thing to do.

Beyond that, you basically work your way up the ladder of components. First, check the hard-drive by: (1) booting into a recovery-disk or LiveUSB/LiveCD and do a full scan of the hard-drive; and, (2) try to get another hard-drive (maybe from an older computer) and swap it out to see if it works fine with another hard-drive. That will rule out the hard drive as the possible issue, which makes RAM the next component to check. This you can do by removing them individually and going by process of elimination until you figure out which one (if any) of the RAM stick is the problem. After that, try swapping out the graphics card for another one (if you have one laying around or can borrow one) to see if that is the problem. And after that, you must assume that it is either the CPU or the motherboard that is the issue, and that is not really something you can repair or replace easily on your own, so you'd better go to a repair shop or demand repair or refund by the people you sold that computer to you (i.e., a computer is not supposed to break after 3 months, they have to repair it or refund you).

[marek.mikes]

Thank you for the replies.
I dont think the power source is too weak, since the components are not really high-end (GIGABYTE GTX 660 Ultra Durable 2GB, Intel Core i5-3350P, Patriot Signature Line 8GB (2x4GB) DDR3 1600, CoolerMaster N300 case and one hard drive and one dvd drive).
The bios restored itself from some backup unit on the motherboard - it's probably an older version than i originally had, but it happened with both versions.
Thanks for the recommendations for identifying the problem. Trouble is, the problem is very inconsistent and I have no idea how to recreate it. Also, seemingly random things seem to fix it (once it just booted after some time, once it started booting once i switched the power cord (which has probably nothing much to do with it) and now it started working after I've tinkered with some cables on the mother board) so if I really did change components after the problem occured, I have no way of knowing if the component was at fault or if it was just that I've fiddled with the inside of the PC.
So I will probably try to get it fixed at the store I bought it, but I picked the components by myself, so I'm not sure, they'll take it as a whole.
I still think the power source might be faulty, since the PC seems so dead when it happens (no fans spinning, no diodes flashing). Would you know of a way how to check the power source for trouble?

[mike_2000_17]

I'm sure there are ways to check the power supply for issues. But anything I can imagine would involve appropriate equipment (to measure the voltage, to provide an electrical load, etc..).

I dont think the power source is too weak, since the components are not really high-end (GIGABYTE GTX 660 Ultra Durable 2GB, Intel Core i5-3350P,

Your graphics card is rated as drawing 450W, and your CPU is rated as drawing 69W, that 519W right there, and that doesn't even count the HDD, motherboard, and the rest (e.g., main fan). Of course, these are "max" power ratings, but still, a good power supply needs to be able to provide that power in case it's needed. If your power supply is too weak, sometimes you might get sporadic drops in voltage which could cause random components to misbehave at random times (i.e., basically like flickering light-bulbs, but in your computer). That could explain some of the weird behavior.