https://i.imgur.com/mWy2uHH.jpgMy fancy new rig has 1x radeon hd 7970, and 3x radeon r9 290 video cards for a total of about 3000 kh/s. It's been mining dogecoin for a couple weeks now, but I just finished its latest configuration yesterday with all 4 cards running on one motherboard with two power supplies.
Full specs:
vga: 2x PowerColor AXR9 290 4GBD5-MDHG/OC Radeon R9 290 4G
vga: 1x XFX R9-290A-ENBC
vga: 1x XFX 797A-TDKC
mobo: MSI 970A-G46 AM3+ AMD 970 SATA 6Gb/s USB 3.0 ATX
ram: 8 GB DDR3 1600
cpu: AMD Sempron 145 Sargas 2.8GHz Socket AM3 45W
psu: CORSAIR HX Series HX850 850W ATX12V 2.3 / EPS12V
psu: CORSAIR HX Series HX750 750W ATX12V 2.3 / EPS12V
risers: two 1x powered, one 16x powered
total cost: about $2100
https://i.imgur.com/0Ir42oN.jpg