Need HELP!

[Genesis15]

Ok my computer was being stupid and saying "Video Cables Connected?" and I couldn't figure out how to get it working, so I bought a A64 2800+ a Chaintech Nforce3-250 Motherboard and a Antec 300W PSU. I put them in and just got them today. Everything was setup and my computer wasn't starting it would turn the fans for a couple secounds then shut off. So I took the video out and they turned, I put in my Geforce 4 Ti4200 and they didnt turn eigther. So I took that out.... When I got the 6600GT working with the computer the video still said "video cables connected?" and it isn't my monitor I know that for sure.

 

[montag451]

Clear CMOS with power disconnected.

Try again.

If no luck - are you completely sure that the cards [graphics] are in working order?
Can you try at least one of them in another system just to see if it boots?

 

[Genesis15]

Video cards are fine have been tried in another system the motherboard is new so IDK how it could be the CMOS

 

[aGreenAgent]

It sounds like your power supply, actually. 300w may be too small for a beefy A64. What's the current on the +12v line?

 

[montag451]

Firstly, ALWAYS reset the CMOS when you get a new board.
Secondly, it is possible to get a dodgy new board shipped to you, or damaged during shipping, or whilst unwrapping, or a tiny piece of bad luck struck the board at some point.

Reset BIOS, then try a boot - if no luck,
Disconnect EVERYTHING from the board apart from:
psu/cpu+fan+hs/pwer switch/case speaker
Do you get any beeps?

If yes, add RAM - do you get beeps now? how many? Please post all results
If no, then you know the problem is psu, mobo or cpu.