The public eth miner is fine. It is already optimized. You want to get something other than 390x. Fury's would remain cooler mining eth. If not cool enough with box fans you could use the fury x. Will get 30 mh's. Fury only use less than or about 200 watts mining eth. Nano's probably won't have as good as resale value, and will get much hotter. Nano wouldn't perform as well on other algos either.