You could always take a measuring tape and measure from the left to right if you really want to find GPU compatibility, but I think it should fit most graphics cards with 2 fans or less.
As for the motherboard, you would immediately know that it can fit a regualr ATX sized motherboard. Same goes for the power supply. Just get a power supply of the same size. It should be able to fit these power supplies
http://pcpartpicker.com/parts/power-supply/#t=2,4,5