Build a PC Computer turns off after around 0.5-1 seconds


TS Enthusiast
I generally keep my computer on all day, so I only have this in the morning, but thats the only time I turn it on, basiclly, its like starting an old car, press on, goes on for around 0.5-1 seconds, then goes off, press on, goes off press on, goes off and so on, however if I do this enough times (literally... sometimes 5minutes of pressing and hoping) it turns on, and works perfectly for the rest of the day.
Its only started doing this within the past week, and I have no idea why it is.

I've tried:
Taking out and putting back in the Mobo battery (after waiting 30 seconds)
resetting BIOS to factory settings
checked the physical power connections outside and inside the computer, can't see anything abnormal
checked that the power switch isnt sticking in

I'm not very experienced with computer hardware, and simply trying another PSU isnt an option really :S so are there any obvious things I'm missing?
Thanks for any help :)

Ps. my next idea I'll try tomorrow, I've set in my BIOS to be able to boot from PS/2 mouse or keyboard, so I'll try that and see if it can boot ok from them, if so, it means its the powerswitch itself

edit: Power on by PS/2 keyboard or mouse didnt work, they just didnt power it on :(


TS Special Forces
Try using one RAM module at a time in the appropriate slot, of course, and see it that makes any difference. If you don't have access to other parts like another PSU to test with, you may only get so far in your ability to diagnose this.


TechSpot Paladin
Unfortunately the power supply might be the issue. I had something similar happen to me a number of years ago, except after turning on and off repeatedly it shorted out my motherboard and a capacitor in the PSU blew. :(


TS Enthusiast
I had been secretly very scared that turning it on repeatedly to get it to boot may be bad for it... I dont have the money for a new PSU really... but if it will definetly fix the problem, I'll definetly get a new one. Are there any ways I can test that its the PSU?
Its just a shame, and very frustrating, because as soon as it actualy does boot, it runs flawlessly.


TS Enthusiast
Anyone else able to give ideas/confirm the currently suggested ones? I really dont wanna spend out on a new PSU only to find that something silly like... plugging in a cable would fix the problem.

Whats most frustrating about this problem, is that nothing caused it, it just started doing it, and slowly at that, just a few failed starts then a few more, and more each day, I fear it'll stop turning on soon :S


TechSpot Paladin
If it was just a cable, the system would not power up at all, or there would be something missing (like a DVD drive, hard drive, etc). Unless of course it was barely plugged in and the minute vibration of you pressing the power button jostles the cable in for a split second.Plug and unplug everything one cable at a time, reseat graphics cards and CPUs (the later if you're confident enough to do so, otherwise just wiggle the heatsink carefully) then try again.

Also, if it has been getting progressively worse, it is a tall tell sign that something is failing.


TS Enthusiast
I needed the computer to boot quickly this morning, so after I tried reseating all the RAM to no avail, I just resorted to pressing the power button as many times as necessary, interestingly, it turned on after only a few tries.
Tomorrow when I have the whole day to myself, I'm going to give it a good clean from all dust, and if that doesnt help, do as you say, disconnect and reconnect everything as much as I can. I can't stand not having a reliable computer... :p
The 1st thing to do - in my opinion - before spending any cash would be download & run MemTest {free!) - you'll need to burn it as an ISO to a CD or DVD (or Floppy if you have one) and boot from it.

Let it run a full test (1Hour or so). If it fails, remove 1 stick of RAM & Repeat. If it fails, try the other one. That will determine if you have faulty RAM - which can cause exactly what you've described.

If it passes, then download the Diagnostic for your brand of Hard Drive - Seagate = Seatools, Western Digital = WDDLG etc and run the long test. If it fails, there's your issue. BACK UP & get a new Drive.

Make sure you have no Bulging / Leaking Caps on the Mainbord - here's a pic of faulty ones:

See if your CPU is overheating. You can use your finger on the heatsink, mind the Fan! - if it's uncomfortably hot, it's overheating.

If all that is OK, then it's LIKELY your PSU, see if you can borrow one & try it b4 you purchase a new one.

All the best


TS Enthusiast
I would have done HD and RAM tests, but I didnt due to the fact that when the computers actualy on, its fine, I mean... completely, I can use all 4gb of my RAM, HD is fine etc. But I think I'll try it anyway, because this morning I've just spent ages doing all I can to clean it, there is no dust I can get rid of, that I havent already now.
I also took apart the front to the best of my ability, and the power switch is properly connected etc, as is everything else, tried reseating etc.
I had a scout for bad caps, I couldnt see anything, and I know my CPU isnt overheating because I have temp/fanspeed monitoring software that says theyre fine :S
If I simply cant do anymore on my own, I'd go to this computer shop I know in which theyd put it in the computer to test it before I bought it anyway, so thats a plus atleast...
I still reckon you should Memtest before taking it to the shop.

I had the exact same symptoms... it'd game AOK, transcode Videos etc, but was a w@nker to start. I assumed the RAM was fine - like you - but I had an iffy stick and replacing it cured all my woes. If only I'd memtested I;d have saved literally days of farting around & annoying the neighbours with my swearing...................

"If thou wert flesh and blood, I would smite thee"....


TS Enthusiast
Right, well luckily I have memtest on an Ubutu disk... and as much as I really dont want to turn off the computer to test it, I have noticed that the computer will boot up no problem at all if it was turned off recently
in fact it seemed to be quite a while after I could still turn it on ok, BUT as soon as it was left with the power switch at the wall turned off, thats when it would be a pain to start again.
Anyway, I'll do the memtest now then, thanks :)
(I have 4 1gb sticks btw, better than 2 2gb ones if one is duff anyway :p)

oh, also, I have tried booting the system with only 1 stick of RAM, but still, I'm gonna memtest now


TS Enthusiast
Well, memtest said no errors, looks like I'm gonna have to spend... :(
tbh, I dont mind if its the PSU, that wont be too bad to replace, but if its the motherboard... :( bye bye computer, Mobo will be too old to replace

Latest posts