Never heard of an Epsilon psu - suspicious.
I just googled Epsilon....its actually FSP's Epsilon line; not a separate brand. So, I wouldn't suspect the PSU anymore.....although that is still possible.
It could be anything that newf said...but if it isn't, I would suggest bringing it back to whoever built it for you. If its a computer shop, they should have some sort of warranty....
Best of Luck