In the picture it says that it is a Coonix pwoer supply, I have never heard of them before.
You are buying prebuilt so you take your chances with the parts. On the one hand iBuyPower would not still be around if the power supplies they were using were crap. At the same time you know that they are using that Manufacturer because of the cost so they have to be skimping somewhere.
If I were you I would google Coolnix and look up some specs about that power supply. Or make sure that you have a warranty for the computer.