I got a pre-built PC last Christmas, but I thought it needed an upgrade so I bought a 750 ti. I plugged it in and turned on my PC. It turns on and lights up on the inside but there is no signal in my monitor. I can plug in my monitor on the other part of my PC (where the old graphics card, an AMD Radeon R7, was) and I get picture but my 750 ti does nothing if I do this. I'm not the most knowledgeable person when it comes to computers so I decided I'd come here for help. Is there any way I can get it to work?