Im buyng some Gpus for my new rig.
Did r290x have much more power than r9 290?
Or same thing for mining?
I picked 3 x 290s a couple months ago, at stock settings I hash about 25 MH. I expect a 290x you might see 28... have to weigh the cost up front. I got mine for 179.00 each.
Now, mine are reference coolers... and sapphires, they suck! lol noisy and they run hot! but they have made me some money and perform good, do what I bought them for. Not sure if they make a dual fan 290x... but go with that if they do. Will be much quieter and cooler. Pull about 1000 watts on a 3 rig system. A cheap 1200 watt will suffice
Same cards here, 26.7MHs @stock with original bios, 27MHs after flashing with optimized bios, but always @stock.
So your 25 is low.
560w for 2 cards ( after undervolt )