power supply issue, no boot, now boots

I am the original owner of this iMac 27" late 2010 model, today I was copying fils from one external hard drive to another external hard drive (one drive has its own power supply the other is a 2.5" laptop drive not self powered).

I was also looking around the net and noticed that the progress bar for the copy had not moved at all and would not cancel, I tried to restart but because it thought it was still copying it would not...I waited 30min, then held the power button down to force a restart that didn't work either, it just sat there, I unplugged it for 30 seconds.

Plugged it back up and pressed the power button and it would not boot at all !

no noise, no fans, nothing.... I searched around found that this model has some diagnostic LED's and looked at those 4 little lights, I plugged it in and looked,

ALL WERE OFF!

LED 1 should be always on if the power cord is in, so I tried another cord, same result. Also tried a different outlet.

I did some more research and my guess is the power supply, I unplugged the computer and came back to it about 5 hours later, plugged it in and it POWERED UP like nothing ever happened!

I ran a program to check the temps, GPU, CPU, SSD, Logicboard ect... and even during a 3d game the cpu got to 120deff and the GPU got to 130degf....

Could I have a bad power supply ? to much current on the USB with the external drives?

I have used them like this before, backing up photo's and such.