I'm building this PC with a 420 watt PSU from Raid Max that came with the case and the following...

Gigabyte 915G mobo
MSI X600XT PCI express vid card
Pentium 4 2.8 GHz prescott core
1 GB RAM (2 x512)

Problem is that I don't think I have enough power according to what I'm reading online. The power supply main power connector is a 20 pin but the mobo takes a 24 pin connector. According to what I've read in the mobo manual and online this of fine as long as the PSU provides enough power you simple start at pin 1 to connect the 20 pin connector.

When I turn it on, the CPU fan spins for about 5 seconds and then stops I turned it off as quick as I could after trying it twice.

I'm pretty sure I just need more power but I'm just looking to confim this before I buy another power supply. Can anyone confirm?

420w should be enough. Did you connect the 4pin power connector for the CPU into the small 4pin connector on the mobo?

Also, if I am reading you post right, it is shutting off after 5 seconds. Did the CPU heat sink come with a thermal pad? If so, did you check to see if there was a protective cover on the thermal pad, and remove it if necessary? Or if you used your own thermal compound, did you apply it correctly?

Are you getting any beeps when it starts up?

Also, make sure the CPU's fan connector is connected to the correct MB fan terminal.

If it is and the MB's CPU fan terminal has a 3-pin male connector, then make sure the CPU's fan has a 3-pin female connector.

Yes, I'm good on all of the above. Thanks.

Gigabyte tech support says there is nothing wrong. I guess the CPU fan will not start running until it goes above 40 C. There is a BIOS setting though, where you can set it to run all the time if you really want it to.

Thanks for the replies.

Good to hear things are working as they should. :)