How do you find out the strain of a PSU?

[Tommy B]

Is there anyway you can find out if the PSU is struggling?

I've got a Levicom 420W powering 3HDs, Athlon 64 3500+, 7800GTX, 2 DVD drives, 4 fans... (and soon to be UV cathode and 2 more fans)

 

[Tommy B]

Thanks for that. I should be OK.