I have been looking at Dual Core power consumption - the CPU in my system could chew up 200w or even more when overclocked to 4.xghz - thats nearly 17A if my calculations are correct?

Add 2 volt modded 7800GTs at around 100w each? Then theres the mobo itself and its components, 5 hard drives, 9 fans, etc etc

My dual 14A rails could probably both be maxxed.

How can I work it out - I have a multimeter?

I know basic electrical equations!

Thanks