I'm pretty new to mining, but I have a few R9 290s that seem to be good bang for the buck miners if you can get them at a reasonable price. The 290x is a bit faster thought so if we can get those it would give us the biggest bang per PCI slot. The way to figure it is figure how much hashing power you expect per dollar on the card with a slight weighting toward the higher power cards because you can only get so many in each PC. So with lower power cards you cost per killahash goes up due to the need for more PCs and thus more electricity to run them. My head hurts too much to do the math at the moment, but it's really all about the price of the card. Whatever card gives the most bang for the buck is the one I'm sure we could all agree on.
I'm currently running 3 290xs, 2 290s I got on deals, a 7970 I got on a deal, and my 3 old 6970s and a5870. I'll have to add another mining PC if I add many more cards, ?I already have to run a heavy duty power cord to the bedroom I keep my miners in because I blow the breaker if I don't. The Sapphire Tri-X 290Xs are outstanding because they have an excellent cooler on them that is fairly quiet. (It stays about 20 degrees cooler than my other 290x without much noise at all) They are great if you mine on your main working PC since you can stand to be in the same room with them. They also overclock well, but I've found that you don't always get more hashing by raising the clock, sometimes you get less, seems you have to find the right combo of GPU clock and Memory clock, but I'm still experimenting there. I just got the cards earlier this week. They are very long though and won't fit in older cases, but since most of us will have to run on risers to get any air to them that isn't a huge deal. The reference design coolers on the 290s suck. The temps are always near 95c and they sound like a hair dryer. Happily I have those in my basement that I hardly ever go down to.
I've read that the 280xs are good bang for the buck miners too, but I don't have one of those yet.
Korxax
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