Computer won't turn on

[lavaxmonster]

Yesterday i tried installing a new video card (ati radeon 9550, to be exact) and after installation and hooking everything back up my computer wouldn't turn on. i figured it was my power supply, seeing how it was only 250 watts, so i went and bought a 400 watt power supply. so i hooked up the new power supply and it still won't turn on, i'm thinking it might be a problem with my motherboard or something.

pc specs:
hp pavilion a420n
AMD Athlon(T) XP 3000+ 2.167 GHz
512 ram
160 hdd 7200 rpm
crappy onboard video card (reasoning on bying a new video card)

if anybody has any suggestion on repairing my comp, please tell me. thanks.

 

[A_DOG73]

did you try the old video card again?

 

[lavaxmonster]

i previously just had onboard video, so i took out the ati and removed the cmos and put it back to to revert to the onboard bios and the comp still wouldn't turn on.

 

[Radwen]

Check for burnt spots on your motherboard, or any other type of damage. Same for your cpu.

Is your power supply well plugged ? Double check, triple check.

Motherboard installation pegs. If it is not mounted correctly, there might be contact with the case (if it's metal) and that would cause your pc to not start.

Check if you haven't moved anything around while you changed your case components.

If it's not the power switch in the back of your psu, it's most likely mobo or cpu damage..

 

[Samstoned]

disable on board video in bios and look for jumper to disable
is this board able to support
4x8x i think that card is dual 1.5V