Reddit mentions of MSI R7850 Twin Frozr OC AMD Radeon HD 7850 2GB GDDR5 DVI/HDMI/2xMiniDisplayPort PCI-Express Video Card R7850 TWIN FROZR 2GD5/OC

Unless your monitors use a DisplayPort connector, you'll need to do things a bit differently.

Firstly, you don't need a 7870. A 7850 will be fine for three monitors. I'd say less than a 7850 might not be ideal. This card's cheaper and has a better, quieter cooler:

http://www.amazon.com/dp/B007MLSGHE/

You'll also need both of these:

http://www.amazon.com/dp/B004071ZXA/

http://www.amazon.com/dp/B001TH7T2U/

Or just two of these:

http://www.amazon.com/dp/B004071ZXA/

Now, let me explain myself. I'm assuming your monitors don't have DisplayPort connectors or HDMI connectors.

That AmazonBasics cable converts HDMI to DVI (which I'm assuming your monitors all have) passively, since HDMI and DVI share the same internals.

That Accell "active adapter" is required by AMD/ATI (same company) graphics cards to use a third monitor, if it doesn't have a DisplayPort input. It converts the mini DisplayPort connector from the graphics card to a more standard DVI connector.

If you do decide for whatever reason that you want six monitors, this graphics card in combination with the Accell adapters will work for you in a single card:

http://www.newegg.com/Product/Product.aspx?Item=N82E16814129262

It's a bit pricey, but the fact that it can run six monitors from a single card is very impressive. You'd of course need six Accell adapters.

albert1854 was probably correct in his thinking, but I know I prefer a lengthy response, so I hope this helps you.

Currently my PC is 6+ years old. It plays all of the games I want but it's tough. Right now I'm playing a lot of Fortnite at mid settings but that's with my video card overclocked as high as it can and the fans are like a jet taking off. I get about 45-50 fps.

My video card is an MSI R7850 https://www.amazon.com/gp/product/B007MLSGHE

I have an i5 2500k cpu with 8 gigs of ddr3 memory

https://www.amazon.com/gp/product/B004EBUXHQ

https://www.amazon.com/gp/product/B004QBUL1C

I assume it is the gpu that is the limiting factor here, what can I upgrade it with that will last me for the next year or two? I figure at that point I'd need to make a complete new build anyway.

I found a 7850 in that price range.

I ended up going for this.

PSU

Graphics Card

And the rest of the PC

Yes... I know it isn't custom made (as it uses a Zoostorm base), but the other parts (CPU, ect) aint too bad on it. So I decided to upgrade the shittest parts