PC not booting

Richard M

Richard M

Richard M

Associate
Joined
27 Feb 2004
Posts
106
Location
Cardiff
Hope someone can help out with this.
Basically when I push the power button everything will turn on for about 1 second and then turn itself off.

I have done the following:

Cleaned out the inside to remove dust with a soft brush
Reset CMOS twice (by removing battery for 20 mins and also by the jumpers)
Replaced the PSU with a better one
Taken out graphics card, RAM, unplugged all disks

None of this has made any difference and it's still doing the same thing.
I just push the power switch, the fans spin for a second and the LEDs on the front panel come on and then it just switches off.
With the graphics card in, the monitor also turns on for a second but then goes back into standby when the PC turns itself off.

Any ideas?
It was working fine last night and I shut it down in the normal way from Windows.
 
Check CPU fan is plugged in. If it is take the fan off, take CPU out. Then reverse process. This has worked for me in the past.
 
I've done this and I also took the motherboard off the tray and screwed it back in to check that nothing was touching the back.
Still getting the same thing - turns on for 1 sec and then turns off again.
It did turn on a few mins ago but I had no RAM or graphics card in, can't figure out why it would do this.
 
^^ agree with Edeath

also, try plugging everything in and just leave it all for a while, then come back and try powering up. My psu turns on for a second, turns off for a few seconds, then turns back on and boots when I have just switched on at the wall socket. When the wall socket has been on for a while, my pc just boots straight away (no power on/off/on) - your problem may be smilar to mine, just more exaggerated.
 
Ok I've solved it!
Now this gives another problem - when I hold in the reset switch with a screwdriver it will turn on but how can I disable the switch or whatever? Or how can I get it to stay held down?
I know about the jumpers that fit onto the motherboard - is there anything I can do here?

I use one of those (old?) Lian Li aluminium cases than have a big power switch with the smaller reset switch underneath.
Underneath this there are the power and HD lights.
 
Just noticed something else as well - the different PSU I put in uses a 20 pin connector but the motherboard has a 24 pin one.
It seems to work fine and power up because all the fans run and the computer is putting beep codes out.
Will using a 24 pin PSU or 20>24 pin adaptor likely fix the problem of it not posting?
 
what psu do you have? If your mobo has a 24 pin power socket then you must plug in either a 24-pin power plug from the psu, or a 20+4 pin power plug.

Your psu may/should have a 4 pin power plug that connects to the 20 pin power socket to create a 24 pin plug (so it is then a 20+4 pin power plug).
 
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