Two 5700xt hashes 108Mhs with 230w to 250w power consumption
Three 5600xt hashes 114Mhs with 255 to 270w power consumption
There's no big difference in terms of efficiency, at least in my opinion
Maybe the new navi cards will increase this efficiency
Most Nvidia cards I used to reduce TDP to 60% without any decrease in hash, but this 3080 looks very hungry power
In my country it's almost impossible to get one, there's no cards to buy, even the 3090 are out of stock
Right now, I would not touch any rtx 3080 at all, too many issues but as soon as the issues are fixed then I will think about buying one. The good thing about the 3080 is that you get a good performance without the need to change the bios, flashing bios can be very painful, I never bricked any but is better if you can avoid that. Also for management 1 card is better than 2 cards, in the long run running systems with 1 card the uptime is a lot better than running with 2 cards, so the uptime the 1 card instead of 2 provides pay off the electricity, I mean, take for example a system with 6 gpus and then a system with 12 gpus. The uptime a system with 6 gpus will be at least 5% more than the one with 12 gpus, also the more density it gives the less you need to spend with a second system, example, motherboards, memory rams, motherboard and so on. It may be unnoticeable for some people but every time a system restarts you lose from 1 to 10 minutes and sometimes you lose a lot more than that, so if a system restarted 4 times per day then you may have lost almost 1 hour and that is a lot. Well it is something to think about.
if i could find a 3080 blower style i would buy two or three. say 3 for 2000 or 2100.
nvidia tend to run more stable.
I have two empty boards. a six slot and an eight slot.
14/2 = 7 slots doing 85 mh = almost 600 mh.
if i use 5700 xt we are doing 7 x 50 = 350 mh.
a lot more hash in the same spot more stable.