3.5 year old system won't power up, at wits end

[Icetoad25]

So I shutdown my PC and went out of town for 2 days. When I returned and tried to turn it back on using the case switch, nothing happened. No fans turn on, no hard drives, nadda. LED on the motherboard indicates it is getting power, though at certain times throughout my troubleshooting process it was flashing instead of solid. Here is what I have tried so far:

1. Opened up the case and checked the connection between the chassis and the motherboard for power, reset, indicator LEDs.

2. Tried booting the PC by shorting the power up pins on the motherboard with a screwdriver.

3. Removed the motherboard from the case. Disconnected all drives, removed the soundcard from the PCI slot. Left the CPU/fan, graphics card, and both RAM sticks in place.

4. Tested the PSU using a tester. The 5VSB remained at 5.2 most of the time but would sometimes reach 5.3 or 5.4 temporarily. This made me think the PSU was the culprit, so I went and grabbed a new one from Best Buy. Once new PSU was set up, tried booting using the Chassis connectors and also shorting the pins. Still nothing worked.

At this point I think the problem must be the motherboard being faulty in some form. It is an ASUS A8R32-MVP Deluxe. Am I correct or is there something else I can do before going out and buying a new board?

 

[Icetoad25]

Update: Nevermind. I must have overlooked something after I installed the new PSU. It seems to be working with the new one, so the old one is the culprit. Guess the 5VSB on the old one is shot (Enermax Liberty with 3 year warranty that is 6 months outta warranty).