setting up crossfire with 2 AMD Radeon HD 7970

[Latios]

hello readers.

im new to the world of PC building so please go easy

i did research it first before asking but i only found results that weren't relevant e.g crossfire with 2 different cards...

im building a PC thats supposed to be able to play most games, however im stuck with the graphics cards, i have 2 identical ATI Radeon HD 7970's and want to setup crossfire but i don't have a clue about how to do it and whether my current specs may affect it.
i cannot afford a high end GPU hence why i resorted to xFire
im also looking for advise on a good motherboard and PSU as i know these need changing
also i should point out that im not looking to run games at 150fps with maximum settings at 4K, only dual screen

specs:
Intel Core i5 7600K with Corsair H55 cooler
ATI Radeon HD 7970 (only one is installed)
Gigabyte B150-DS3H LGA1151
Corsair Dominator Platinum 16GB DDR4
corsair VS550 550W PSU

(also i found a tiny switch next to the bridge contacts, marked "1" and "2")

thanks in advance

 

[Zerk2012]

For the price of a new board, power supply, and potential new copy of windows you could sell those cards and buy a nice GTX 1070.

 

[Supahos]

Wellll. Board only has slot for one card, one card can use up to 375 watts you only have 550w. Your mother board may or may not support your CPU without a bios update that you can't do without a different processor. That CPU costs more so you can overclock it but can't overclock it on that board.

 

[Calvin7]

HD 7970 CrossFireX
850 Watt Power Supply is recommended for CrossFireX System
4 x 6-pin AUX PCIe Power Connector

The tiny switch next to the bridge contacts, marked "1" and "2" is for turning on an overclocked BIOS. They also have a OC Utility to adjust OC.