Bad mobo, low voltages?

[Toxicfunk314]

I recently replaced some of my pc parts and had enough random parts laying around to build another pc. After about a month of non-use I built the pc and installed Win7.  Shortly after first boot I noticed that the Pc was occasionally freezing for up to ten seconds and then becoming usable again.  After some perusing, I found that the 12v rail is only getting 8v and the other rails are similarly under-powered.    These are software readings but at the time I didn't have a multimeter. So, I immediately ripped out the 600w power supply and replaced it with a 750w power supply.  Unfortunately, I was still getting the same software readings after the PSU change so I went out and got a multimeter and tested the PSU's both under load and not under load.  Both PSU's are within tolerance.  I can only think of one other factor and that's the motherboard. The system is exactly the same as it was previously, when it didn't have this issue, except for the case and PSU.  Could it be that years of near-constant use and then a month in a box allowed/caused some motherboard components to go bad? 

The system in question:
FX-6100
Asus M5A 78L-M LX Plus (I know....shitty mobo in the first place lol)

8gigs of Corsair XMS3 1333 Ram
Sapphire Radeon HD 7770