Help with my Graphics Card

I recently bought an X51 R2 that bring the gtx 745 graphic card , when I started the computer and click into the nvidia control panel it said to me that there was no nvidia GPU detected , so I  did a little bit of research and found that u need to switch to discrete in the BIOS settings which I did later , but  it keep saying the same error so when I restart the computer to access the  Bios system my surprise was i couldn't access the BIOS system because the alienware logo load screen wont appear so it doesn't give me the option to press F2 , I tried to spam F2 ,F10 , F12 when is restarting but nothing happen it just straight up appear to the welcome window , So I tried to access by recovery advance start up , then troubleshooting then advance option and finally  click where it say UEFI Settings which is supposed to restart the PC and let me access the BIOS system by pressing F10 but when I hit restart the PC will restart but never came up again it remain on with all the lights but the screen is black and it says that there's no signal detected is like the computer is off . Any suggestion on what I should do in order to switch form the intel graphics to the Nvidia one or fixing the restarting problems to access BIOS (WINDOWS 8,1) 

Btw: I opened and check the G.C and it didn't say Nvidia but it did say GTX 745 it has a red panel , and also some other numbers that I typed and it appears to be the nvidia card ( in manage devies the name nvidia gtx 745 appears)