Computer won't start

Hi,

Our main computer is acting kinda funny and not starting up at all.
When the computer is getting power, without me even turning on the pc, it keeps going on and off again every 5 seconds. The only way to stop this is to disconnect the power source.

Usually, with a successful boot-up, the computer beeps once. But now there are no beeps at all.

It has happened before in the last few weeks that the computer would not start up properly (no beep, just fans spinning). But in those cases I would just disconnect the power and turn it back on an hour later and it would work.

I took out the PSU and vacuumed it from the inside. I swapped the RAM sticks and taken out the video card + tv tuner and disconnected the dvd drive with no luck.

 

It sounds to me like a bad Power Supply(PSU). Do you have another one that is known good that you can try?

 

I've got one from an old computer. I'll see how that one goes.

Thanks

 

umm the older PSU only has a max output power of 250W. Whereas this one has 350W. I'm guessing 'under-powering' wouldn't destroy anything?

 

I replaced the PSU with the old one. I ran into a 'small' problem..
The broken PSU seems to provide power directly to the hard drive whereas the old PSU that I used to replace it doesn't have the same connection to provide power.

Anyway, I still provided power to the PSU. Once I attached the cable the fans started running instantly, without me actually pressing any on button... holding the power button for about 5 seconds shut everything down again though.
then after 15 sec I turned it back on and only the fans started spinning again. No further progression.

 

I'm not an expert with these, so I can't help here.
But I can mention an issue that I've seen before.

A vacuum produces static electricity that can gather at the end of the vacuum wand. This static electricity can damage any electronic components that it comes close to (doesn't even have to touch it). There's electronic components inside of the PSU.

And, just FYI, don't use an air compressor either - as the high powered air can easily damage weak components that it comes near.

Good luck!

 

i doubt it's caused by the vacuum because it was already broken before i vacuumed. but yea, all I can think of for the computer not working now is either:

*PSU is not powerful enough (350W previously vs 250W now)
*PSU doesn't provide power to the hard drive (any drive incl dvd drive)
*Problem doesn't lie with the PSU (In which case there's a hundred other possible causes.


edit: I've got one more PSU to try. It does have the right connectors for the hard drive and its 400W. So if it still doesn't work then it must be something else.

 

with the latest PSU in place I've got some progression. When I take out the GPU I get one long beep followed by I think 2 really short ones. when the gpu is attached nothing happens again.

 

One long two short is supposed indicate a problem with video.

Are you plugging the video cable into the addon graphics card or into the port built on the motherboard (if it exists)?

Can you examine the addon graphics card you are using?

http://img844.imageshack.us/img844/79/img184h.th.jpg

A bad one will look something like the above. See the busted capacitors? Even if they are somewhat bulging it could indicate a bad video card.

 

no capacitors seem to be busted on the motherboard or the gpu.
I put the original PSU back in, and it is behaving the same as either one of the other PSUs. I'm guessing the problem doesn't lie there.

so whats happening now:
everything installed - everything is spinning up, but no beep, no screen.
video card taken out - 1 long 2 small beeps (indicates video card or possibly RAM issue, since the video card is not installed i guess it's referring to that)
video card and RAM taken out - everything spinning up, no beep, no screen
video card out, 1 RAM stick in - 1 long 2 small beeps

 

As suggested by the 1 long 2 short beeps pointed out by thisisu. Do you have another Video Controller you could try or the onboard controller if it has one?

 

It hasn't got an onboard video card, I haven't got any other video cards that fit either.so tomorrow I will go to a computer repair shop and see if they can pop one in for me to check.

Lets hope for the best.. And that it is the gpu that's broken.