nEVER MIND ITS NOT THE psu. changed psu and still happens sorry.
I bought a Smart BX1550W from Newegg back on 1/24/2000 and now its causing constant random restarts and shutdowns. After pulling my hair out for several days trying to figure it out, I installed a test PSU and the PC works fine. I didn't think it could be the PSU because it is not old at all. My only problem is the warranty requires me to pay shipping. I paid $45 for the PSU and the shipping is $25 to send it in so its not really worth it. I am reading amazon reviews on the SMART series and lots of people are having this same issue. I talked to one of the Thermaltake CS reps yesterday which took 10 phone calls and several VM messages to get someone on the phone. I told him the shipping cost makes it not worth it to send it in and he said "Yea, you're right". Wow that blew me away when he said that!
I feel Thermaltake doesn't stand by their products. If this is happening to lots of users Thermaltake should provide a better method of helping customers. 13 months is a terrible lifespan for a PSU. So my option is to pay almost as much as a new one to send it in just to get another one which will probably not last long. That really sucks for the customer. I would obviously never but a Thermaltake product ever again.