Welcome to Tom's Hardware Forums,
The most likely cause for early PSU death (two weeks is early) is a poorly designed (or built) PSU. I won't ask what the make and model of the replacement PSU was but I will recommend replacing the PSU with one of these brands, Antec, Corsair, FSP, SeaSonic, SuperFlower or XFX. But check the reviews - this is a great site for that
http://www.realhardtechx.com/index_archivos/Page541.htm - on any unit you're interested in buying as even within those brands, there may be 'lemons'
Hope it helps