samuel00102 :
All atx power supplies are standard so id suspect it would fit
This is not correct. While officially speaking ATX power supplies have a maximum length (off the top of my head - 140mm), many "ATX" PSUs exceed this which will potentially cause issues in a case like the Prodigy M.
The Supernova G2 is 200mm long.
The only way to know if they will fit is to know exactly how long the graphics cards you want to fit in are.
Will the XYZ Power Supply or ZYX Video Card fit inside the Prodigy M?
Video cards at 9.5inches or less will have 200mm of power supply clearance
Video cards at 11 inches or less will have 160mm of power supply clearance
Video cards at over 11 inches will have 150mm of power supply clearance.
A reference GTX780Ti is 10.5inches, so going purely on the info supplied, it seems very unlikely you'll get a fit.
On a slightly different note, I'd be very sceptical about doing builds in the Prodigy M in general. It's a poor choice for SLI due to it's weird layout and poor airflow, not to mention the lack of support for some excellent PSUs. There's also the issue that if you install an optical drive, you can't SLI, meaning that often the original Prodigy offers far better characteristics (though it's obviously poorly suited for your plans).