I have this PC http://www.newegg.com/Product/Product.aspx?Item=N82E16883229285
and I was thinking about buying a gtx 560 ti. Will it work with its PSU, case, etc.? Or will I have to upgrade?
The gtx 560 ti is power hungry, a quality 500w would get you by, but the brand is not listed.
Can you open your PC and see what the brand is, and the amps on the 12+ rail are? There is usually a sticker that gives information on the power supply itself.