Cant turn mac off like it should Bluescreen loading

[Cumsume]

hey im new to this an i bought
http://www.amazon.co.uk/dp/B0098VKIRC/?tag=tonymacx86-21
on my Mac Pro serval weeks ago

Processor 2,8 GHz Quad-Core Intel Xeon
Memory 16 GB 1066 MHz DDR3
Graphics NVIDIA GeForce GTX 660 2048 MB <- the card linked above
Software OS X 10.8.3 (12D78)

now when i shutdown my pc the graphic card keeps current "power"
and wont shutdown
when my mac is loading some things i get this loading Blue screen

i did the basic installation of the Tonymacx86 app
the moutain lion eddition offcourse

any ways to solve the problems im experiencing?
thx

 

[Cumsume]

please help me i want to be able to shut down my pc like it should : /