Ballpark maths.

Radeon 7: $700. 84Mh/s at 230w.

Navi: Assume $300, with 8gb ddr6, similar performance to Rtx 2070. Assume 42Mh/s at 115w.

6x Radeon 7 rig: $700*6 + $400 psu + $200 mobo,ram,cpu = $4800 (504mh/s at 1480w - 1380w + 100w rig)

8x Navi: $300*8 + $250 psu +$200 mobo,ram,cpu = $2850 (336mh/s at 1020w - 920w + 100w rig)



6x Radeon 7 - $7.75/day profit at $0.075/kwh, 619day ROI

8x Navi - $5.10/day profit at $0.075/kwh, 558day ROI


For me I recently bought a bunch of Vega 7s because I could get them at $670 usd + sold the games and my cost basis was $635~. Plus half the cards, half the problems, half the work imo.