Running a test rig with 1 Sapphire RX 480 8 GB connected directly to H81 BTC Pro motherboard w/o any Molex to the MB. It's been stable at 28.5 MH/s at 2300 MHz memory clock for over 24 hours, no external fan. Rest of the controls are grayed, perhaps a new version will allow undervolting. Noise wise it is not more than 390 running at 70-80% fan speed. It is going to a 6 Sapphire 8 GB rig once I build a wooden frame. GPU only power usage 170-175 watts at the wall, I am sure it will be better when I use quality PSU. Running Claymore's miner in ETH only mode.
Hardware: Sapphire RX 480 8 GB, H81 BTC Pro MB, 4 GB RAM, Celeron G1840, Win 10 pro, using a spare 1000 watt Antec Gold PSU.