Just cause it was running your old system fine doesnt mean it isnt failing. Its at least 4 years old, do you think PSUs get better with age? They degrade. Try a different PSU.
Looked up failing PSU symptoms and you're right. I just hope I haven't endangered my new mobo giving it dirty power.
What PSU should I get for these final specs?
Phenom 960T overclocked to ~3.6ghz
4gb Gskill PC12800 DDR3
Nvidia GeForce 560 w/ 1gb
1 Sony DVD drive
1 Hitachi Deskstar 320gb
2 90mm case fans