P4r4gr4ph

If you are riding the edge of what the PSU is capable of, yes... a few watts can make a difference.
 
Its almost like nobody here understands that PSU's have more operational states than dead or alive.
 
Voltage regulation is much more than what you read on a multimeter.

Overloaded PSU = voltage droop = out of spec core/vram/display controller voltage regulation.  Its pretty simple, and is known to happen.