Can anyone explain how I would put TWO graphics cards in a single PC?

[Tokui]

Is there anything extra I need to do? Do I just plug it in? What?

 

If you need the specific GPU, it's a 980 ti. 

 

 

 

 

[comicsansms]

Depends on the motherboard and GPU.

A 980ti AFIAK you can have 4 of them in SLI.

[byalexandr]

You need to have two correctly spaced PCI-E slots, both at 16x or 8x. You need a power supply capable of delivering the power, a CPU capable of not bottlenecking it, and an SLI bridge.

[Atmos]

If its a nvidia card, and you want two, then you plug each into your motherboard, connect both to power, then connect the two gpus with an sli bridge. and make sure sli is functional in the manager.

 

If it's a high-end AMD card, then you just put both on your motherboard, and connect them both to power. Then make sure that crossfire is enabled in the manager. But if the card is not a 290X, 290, 390X, 390, Fury Nano, Fury, or Fury X then you will need to attach the cards once their in the system with a crossfire bridge.

 

In both setups, you connect display to the top gpu.

[Lethal Seraph]

See your motherboard manual for a specific slot for a single, dual or triple GPU setup.

[User1868]

You can only put GPUs with the same core (at least that is what I've heard). Since you are going to have the same model you should be fine. Make sure your mobo supports sli (and how much) and make sure you have enough space and enough power

[Sauron]

You plug it in and plug in the sli bridge in both cards

[TheAmazingCookieFromSquare]

Shove the other 980Ti in the lower slot then attach the sli bridge then enable sli in NVIDIA Controll Panel and then there you go 

[mikat]

maybe this will help: http://linustechtips.com/main/topic/197327-the-sli-information-guide/