I used the nicehash miner with Win 8.1 and Crimson 16.9.2. The AMD R9 390 is just 10S/s. The memory usage is just 25%.
You cannot use all of your memory because all of the zec miners are under test and not stable yet.
I use the nicehash miner with Win10 x64 and Crimson 16.9.2. Amd R9 390X 18.2 Sols/
The nicehash miner is quite slow. The Genoil miner is about 30H/s. But that is not so stable now.
The fastest publically available miner is the Claymore miner. It has 2.5% fees. But it is worth paying the fee.