Computer startup problem

[kirottu]

My brother's computer shuts down right after you turn it on. It stays on just for couple of seconds before it shuts down, no warning bleebs or anything. It did make some weird sound when it was still working, like something from a fan going broke perhaps, but all fans at least seem to be working.

 

Stuff we have tried:

 

• Cleaning everything
• Changing the power source
• Changing the power cable
• Changing the video card 

[Gorth]

Hmm... tricky one that one. Desktop computer?

 

Does it start the POST (i.e. show BIOS information, hardware info etc.) or does it die even before showing anything on the screen?

 

Has it been exposed to lots of G's or power surges?

 

How old is it?

[Janmanden]

Sounds like the PSU is probably failing and if that's the case it could severely damage your brother's system if you keep fiddling around with it unless the PSU got some form of protection vs. power failures, overloads and so on. I had a PSU from Chill Innovation fry two of my Graphics Card, totally melted all transistors, before I noticed that surge of energy it spat out on Power Up.. 

 

Might be a defective or detached component somewhere. Maybe the memory Sticks or CPU are loose. If at all possible you could try to load the system with a minimum of components, remove some memory sticks and detach all non-essential parts to save power and remove the number of culprits. Perhaps resetting the CMOS and load the system with a default setup of some kind.

 

Argh, those bullets pierced my eye balls... Missed the changing psu's part.

Edited February 13, 2013 by Janmanden

[Luridis]

Have a look at the CPU fan as well. CPU's will over-temp very quickly if the fan isn't working and the internal thermal protection resets the system.

[Gorth]

Have a look at the CPU fan as well. CPU's will over-temp very quickly if the fan isn't working and the internal thermal protection resets the system.

 

Yeah, did that on my previous PC (by accident, not design). Trying to find the two pins to shortcircuit on the ATX cable to boot it up without having everything in place yet. Ran for all of 3 seconds before CPU turned hot and shut down the system.

[Humanoid]

By changing power source, do you mean actually changing the PSU or just trying a different wall socket?

 

Thermal protection was my initial thought too, but the OP seems to indicate all fans were spinning (though check the PSU fan too, it may be non-obvious). At least we have that now, in the original Athlon days, 3 seconds is more time than it took for your CPU to burn in a plume of blue smoke.

 

If you have access to a multimeter, try taking voltage measurements from the back of the ATX power connector to the motherboard.

 

 

Other random thoughts:

- No beeping means it's unlikely it's the RAM (unless there's no PC-speaker present), though if multiple sticks are present, take out all but one and try each individually in the first DIMM slot.

- Do you get any video output at all during the two seconds it's on? Thinking if so, it's less likely to be a CPU issue.

- Whenever I see a power issue, I tend to think it's 50:50 on either the PSU or the motherboard, though granted most of my failure cases tend to have been totally dead motherboards instead of the odd two-seconds thing.

[kirottu]

By changing power source, do you mean actually changing the PSU or just trying a different wall socket?

Both now.

Thermal protection was my initial thought too, but the OP seems to indicate all fans were spinning (though check the PSU fan too, it may be non-obvious). At least we have that now, in the original Athlon days, 3 seconds is more time than it took for your CPU to burn in a plume of blue smoke.

 

If you have access to a multimeter, try taking voltage measurements from the back of the ATX power connector to the motherboard.

All fans are indeed spinning and no multimeter. 

Other random thoughts:

- No beeping means it's unlikely it's the RAM (unless there's no PC-speaker present), though if multiple sticks are present, take out all but one and try each individually in the first DIMM slot.

- Do you get any video output at all during the two seconds it's on? Thinking if so, it's less likely to be a CPU issue.

- Whenever I see a power issue, I tend to think it's 50:50 on either the PSU or the motherboard, though granted most of my failure cases tend to have been totally dead motherboards instead of the odd two-seconds thing.

Ram thing didn't help and it is indeed just couple seconds without video output.

 

I'm pretty sure PSU went wonky and short circuited something in the motherboard. Meh.

[Bokishi]

I had my PSU kill 2 mobos awhile back, make sure to use that new psu with a new mobo to avoid future problems 

Edited February 15, 2013 by Bokishi