Alienware x51 r2 Possible graphics card issues.

Hey guys I've had my x51 r2 for a few years now and just decided to do some upgrades to it, I added 2 8gb kingston hyperX Fury ddr3 sticks of ram and it recognized it no problem. I was planning on replacing the hdd  with a 4tb 3.5in hdd but I wanted to add a second one in there to boot from and give me an extra 1.5tb so I bought the cords(4pin molex to sata power cable adapter, 4pin molex male to 2x 4 pin molex female power y splitter, and a sata8 ata cable) and wired up an old external hdd that I took out of the case(not sure about the height but it's about the size of two laptop hdds stacked on top of each other). From there I started it up with a windows usb stick inserted to install the operating system. I got all the way through the installer, shut down the computer and pulled out the usb stick and then powered it back on, and it got to the alienware splash screen where it gives me the option to press f2 for bios and f12 for start up menu and then just goes black. I've tried getting into both the bios and the start up menu but I got a black screen both ways. I thought maybe I had screwed up something in the installer so I tried to reinserting the thumb drive but I was still got the black screen and couldn't even go through it. After this I got a little freaked out I had screwed something up so I took out the extra cords and reinstalled the original hdd and now am still getting the same issues. Turns on, one beep, splash screen, and then black screen. the graphics card I have is the gtx 745 and I have been using a VGA connection with my monitor, Since I ran into this issue I've tried connecting it with the hdmi (which is not apart of the 745) and still have no luck. I had originally placed the 1.5tb hdd on top on the 4tb but decided to switch it out with a lap top hdd that would fit on top of the optical drive because of how close it was to the graphics card, it wasn't touching and it worked when it was there but could that have over heated it? I left the cover off and started it up and the cards fan starts but it doesn't seem to be working. I'm not sure if this is a graphics hard issue or if I tried doing to much with my motherboard and fried it or what. Unfortunately I don't have another rig to test the card on so I was wondering if anyone had any ideas. Sorry for the long post but I figured every little detail could hopefully help!