If you mean the "paper-clip test", it's useless. You need a proper and thorough tester.
Tested it by jumping it, and it was fine.
I'm using the Apevia but I don't wish to debate whether or not it is the absolute best. It works and works well. http://www.newegg.com/Product/Produc...upply%20Tester
The Motherboard wont even POWER ON
It is the PSU. For sure.
I have a lot of experience with equipment that works for awhile and then goes south all of a sudden. Right now, manufacturers are pumping out product of secondary quality and then dealing with the returns. And it does not seem to matter if you stick with quality manufacturers or not. The only time it matters is how courteously/efficiently the mfr. deals with returns.
Some like CoolerMaster and Corsair are wonderful. Others like Gigabyte are ... (sorry, no vulgarity permitted on OCN)
My PSU was a CoolerMaster 1,000 watt (80%) which functioned for a couple of weeks. Then the computer just suddenly shut down. Next, it would not even boot up. And finally, no lights on the mobo, no nothing.
If you do need to RMA the PSU, and you will, I would suggest the US Postal Service over UPS. Why? The much maligned USPS will ship it by air overnight for about $10.00 while UPS will charge more and take at least a week.
Good luck. Buy yourself a tester. You're gonna need it - now and in the future.