PC powers off on boot

[TrialAndError]

Hi

I have a problem where my pc is powering itself off on bootup.
I can usually get to the bios splash screen before it powers itself off.

This is what i have noticed:

I built my system over 4 years ago and everything has worked fine till now.
Latest upgrade was a video card which was 5 months ago.

Yesterday when i switched on my pc it powered itself off straight after hitting the bios splash screen.
I then retried the power switch and it powered up and worked as normal.
I had my pc on for about 8 hours and then sometime in the night windows started shutting down automatically. My pc then powered off. Powered back on and hit the splash screen before powering off again.
(All without me touching a thing).

Now i always get this sympton where it just powers off.
I have noticed that if i take out the power cord from the pc for a few minutes and put it back in my pc wont even register me hitting the power switch (Although my motherboards LE2 light is on)
Then if i wait a few minutes it does power on before hitting the bios screen and powering off.

What i have done so far:
I have stripped my system down to just my motherboard, psu, cpu and ram.
I still recieve the same problems.
This leads me to believe the fault is in one of those components.

I would appreciate any help on trying to diagnosise the cause before i spend any money on replacement parts.

Worst of all is i dont have anybody who is willing to let me try my parts out in their pcs to see what is the faulty component.

[k9bliss]

Need a list of pc system, including power supply. Like, mobo,memory, os, video card, cpu,ect. Brand name or home built.

[TrialAndError]

Thanks for the reply.

I knew there was something i forgot to mention in my post :S

PSU: Some cheap 300 watt one. No brand name.
Mobo: Supermicro P4SAA
Memory: 4 x PC-3200 512mb (Corsair VS1GBKIT400C3 - i think...)
CPU: Intel P4 2.8 (Not hyperthreaded)
Video Card: ATI Radeon X1600 pro (Have tried replacing with old card: Radeon 9500)
OS = Win xp pro

Was originally custom built from systemax but the majority of the parts have all changed since then.

Is there anymore information that will help?

Note: When switching on the system i checked to make sure all fans were spinning so it wasnt a too much heat cut off problem.
All the fans seem to be working fine.

[chipdip]

PSU: Some cheap 300 watt one. No brand name.

Thats not good, try a different PSU, if anything.

[TrialAndError]

Do you think the reason why its failing to power up now is that the psu has just gone wonky?

Everyone i talked to said they were surprised it provided enough power for the components i use. But the thing is i have used it for 4 years without any problems.

A friend of mine is bringing his enermax 450 watt psu round on tuesday for me to try out so i will know for certain if that was the cause then.

The main thing that stumps me and my friends is why my pc didnt just switch off immediately but instead shut down windows properly (log off then shutdown) all on its own.

[Cricket]

Originally Posted by TrialAndError Do you think the reason why its failing to power up now is that the psu has just gone wonky?

Yes. Cheap power supplies aren't known for their ability to last a long time.

Originally Posted by TrialAndError Everyone i talked to said they were surprised it provided enough power for the components i use. But the thing is i have used it for 4 years without any problems.

Doesn't matter if it lasted 4 years, parts do wear out...even electrical ones. Cheap power supplies tend to barely put out their advertised power and your 300 watt PSU was probably running near it's limit over the last 4 years. Running almost full-tilt means that it was generating a lot of heat and heat is generally considered the enemy of electronic equipment. You're actually lucky it lasted this long.

Originally Posted by TrialAndError A friend of mine is bringing his enermax 450 watt psu round on tuesday for me to try out so i will know for certain if that was the cause then.

Yes, swapping in a known to be working PSU is one sure way to determine if your PSU is causing the problem.

Originally Posted by TrialAndError The main thing that stumps me and my friends is why my pc didnt just switch off immediately but instead shut down windows properly (log off then shutdown) all on its own.

Did you run your security scanners? Almost sounds like you have some variant of the old Blaster worm.

Cricket

[TrialAndError]

I hope i dont have a virus.
I use kasperskys internet suite and have run a full scan in the last week.
However the shutdown wasnt one of those which shows an error saying that the system will reboot in 20 seconds etc.
It just shutdown normally, exactly how it would if i pressed the power switch to initiate a shutdown. (Curious...)

Anyway if it does turn out to be my psu then im considering the following replacement:
http://www.coolergiant.co.uk/product...0AWT/index.asp

This way if i decide to build a new pc in the near future then i could at least reuse the psu in that system.
What do you think about that psu do you have any recomendations on better ones?

[flanzig1]

That PSU should work quite nicely. Just remember that PSU has a 20+4 main connector, you will need to seperate the 4 pin connector off to work on your system.