my pc was running fine i had it lieing down and when i moved it to its upright position it turned off. Now when i turn it on it works normally for 5 seconds then the green light on the motherboard goes out (this is not power light, power is still on) then all the fans etc work really slowly and nothing apears on my screen. I have tried swapping power supplies, cpu's and ram. Nothing is making a difference. I am thinking now that it is the motherboard but i do not know how or why?

my computer is

3100+ amd sempron
6600gt 256mg graphics card
512 geil ram
abit nf7 motherboard

Hi jaminporter, welcome to SAF

Sounds like some overheating stuff to me... or a badly hardware setting.
Your comp was running fine for some times, now, what happened just before the problem starts ?

Have you added any hardware, software, or had you some weird thing happening just before the problem starts ?

If you are using Win2k or XP, you may try some restore point.

Chris

Please provide all details, even if you do some different thing just before it happened...

i am using winXP i didnt add any software of anything like that. I did put a new hard drive in put XP on it then turned my pc off plugged in my old hard drive to backup my files. I had my computer lieing on its side for this so i could plug in the hard drives easier then with the old hard drive i was ready to burn my files and i put my pc in the upright position for it 2 burn and it turned off, the pc had been running completely fine until this happend. On my motherboard there is a red light for power, and a green light for when the pc is on. when i turn it on the green light comes on everything sounds normal although i get nothing on screen, then the green light goes off and everything turns off, then the green light flickers and everything comes back on but the fans are moving slower than usual and still nothing on screen

Just a thought jaminporter,

Maybe there is a loose connection someplace. On my old computer, when I plugged the power cord in, it was OK, but when I would move the computer, it would shut down. I found out that the plug inside the computer was loose, they just weren't connecting. There could be something loose that you plug your other cords into, being it was OK when you had it on the side, then you put it upright, now it doesn't work right.

Like I said, it's just a thought.
Lorraine

i just unplugged everything to the mother board and pulled out everything save the connection to the power supply and a stick of ram. The same happens everything turns on then turns off and the green light flickers and the fans run slow

Mmmmm... can be the mobo. As Lorraine said above, it might be a loose connection. I will also look for screws rolling under the motherboard and shorting contacts with the case (I have seen that many times before).

Plugging devices on a motherboard may, if forced, make its bottom to touch the metallic parts of the case and also, crack some circuit tracks.

Also, have you tried laying it on its side again and fire it up? Will it run okay while lying on its side?