Power Supply
 

I'm helping a friend to get his box up and running. I'm not really good at hardware and everytime we press on the power button of the box it comes on for like 3-4 seconds, i can hear the fan start up but then it shuts off again. I was wondering if anyone had a similar problem or heard of that problem and what it could be. I'm thinking the power supply but its turning on for 3-4 seconds, so i have my doubts on that.
If anyone could give a few pointers on this, i'd really appreciate it.


TIA

You can test the Power Supply by shorting the green wire (should be pin 14) with any black wire. Basically, disconnect the ATX connector from the mainboard and just use a paper clip. If it still powers off, start disconnect the connecters from the various peripherals in the computer. If after everything is disconnected and still powers off, replace the Power supply.

If it powers on with out the main board connected, try disconnecting everything but the keyboard, video card and monitor. If it powers on with just that, likely to be an overloaded system. Use the following to calculate the amount of watts you need:
http://www.jscustompcs.com/power_supply/

Thanks a bunch! I'll try that! As always this place rocks!

Futhermore, some motherboards will shut down if they can not detect the CPU fan running.

ok, i tried shorting the green wire with the black and the power supply came on and it didn't shut off. so i removed everything, from video card to hard drive. just left the processor and the memory module in it, it still powers off. the processor fan comes on though but then the whole thing shuts off. i think its probably the motherboard but i just wanna be sure. any suggestions or advice ???

TIA

Sounds like the mobo. Could also be the CPU or Memory, and to be safe I would probably replace all of them. Might want to replace the Power Supply too if it is less than 400w.

There is a non zero risk that the CPU or Memory are bad and can lead to cascading failures. It is less likely to be the memory so you could take a risk and save a few bucks by reusing the Memory. If you do that, run memtest86 for a few hours when the system is up and running.

One thing to do is remove the motherboard from the case and set it on a non conductive service like the foam wrap the mobo problably came with. Then plug in the power, video card, processor, memory. Just the bare essentials, don't connect misc cables or other cards. Now power it up and see if it runs. If it does then either the mobo is shorting out in the case or worst case one of the hold down screws has been over tighten and has damaged the layered pc board. If it powers up then study how the board is to be installed and make sure nothing grounds out. Install the basics again and power up. If all is well then start plugging in the rest of the hardware. One could plug in the hardware one at a time and make sure things startup fine till all is done and the cover is on.

Brian1
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