Verified answer

You should have dual pci-e slots in the alienware and need to buy a bridge connector to hook the two gtxs 680 graphic cards together

Go to http://www.dell.com/us/p/alienware-aurora-r4/pd?re... and they will have that stupid floating box with their phone number. When I was in the planning phases of my build I did ask many questions here. I ran into an issue with my 570 Classified from EVGA. I wasn't sure if SLI is supported. MSI says only Crossfire. The board has a stamp that says True SLI and Crossfire. A quick call to them answered my question. A look at their site for that desktop only says

Motherboard and Chassis Form Factor

MicroATX Motherboard, Mid-Tower ChassisI micro-atx

means tiny and they normally aren't SLI and crossfire compatible due to the board's size restriction.

and doesn't give any specific information. You would need to call them to find out. This depends on the motherboard and power supply unit(looks to be an 850W. No telling the amp rating for the current going to your gfx card. When you are spending any amount of money its' best to go to the source so you KNOW your rights and responsibilities and KNOW what their responsibilities are. Only way to know all this is to call Dell.