That's crazy, I get 29.5 with my 580, samsung @ 2230 memories with 1750 strap.
Samsung is great but you should be mining 30+ at least. Try performance timings, Uber-mix 3.1 is the best.
New to this when you say memory limited do you mean ETH needs more memory, 8GB instead of 4GB ?
Thanks
Not really, if you have more than 2GB it's fine. I think he meant memory bandwith, but it depends on memory clock, timings and core clock. On these RX cards it very depends on timings, just copy straps isn't as good as using performance timings for mining ETH, ETC, XMR etc.