Computer doesn't power up?

[LegendBreath]

Hey,
I just installed a new motherboard for my friend, but it doesn't boot up. :S The LED on the motherboard is only light up at half, it's like if there is not enough power, but the power supply is still a 300W for an ASUS K8V-X, it just doesn't power on. Even tough that I don't have any hard drive or CD-ROMs plug in. The specs:
No brand 300W PSU
ASUS K8V-X
Sempron 3000+ 64Bit
ATI Radeon 9200SE 128MB

Can someone help me on this one? I tough that it would be the additional 12V rail that I need to plug in into the motherboard but no, it's not that, I plugged it in, tried with the one directly from the PSU and with an adapter.

 

[jeremy]

in general 300w should be good enough for that system , however what really counts on psus is the amper rating and psus of same wattage have diffrent amp rating some are more powerfull then others , also cheap psus amp rating is far from accurate..

considering the mobo light is only half on , its gotta be the psu

 

[Law]

Did you plug the P1 connector from the PSU to the MB, the plug is located near your RAM slot. Did you also plug in the Power switch and other switch from the case to the MB correctly?

Then start by starting the machine up with just the barebone component, the CPU,RAM and Vid Card. You might need a keyboard too, some BIOS won't let you pass unless a keyboard is present. See if you can get visual and 1 beep.

 

[Law]

Also, check to see if you actually have the PSU turn on. The correct voltage setting should be 115 for America and 220 for Europe.

 

[LegendBreath]

The mobo gets Power but not all... it's like if that 12V rail is not plugged in.

 

[Law]

What do you mean 12v, are you using that plug top left of your CPU?, you know the one with just 4 holes. You're not suppose too.

 

[LegendBreath]

Well some mobos need to have an aditional 12V right? Cuz on the power supply there is a 12V square plug, and on the mobo to. But anyway, my problem is solved, I've fixed his PC, just buyed another PSU.