We do not use GPU for Bitcoin mining, we use GPU mining rig for Scrypt mining (DOGE at the moment that we will switch to something else if it keeps at or below 0.008 BTC a day at 1600-1700Khash) and 5 ASICs that run total at 250-260Ghash for Bitcoin or any other profitable coin that run on SHA-256. We switch coins that we mine manually or by mining them on automatic port in Multipool or Poolwarz coin switch. We would not dare to mine BTC on GPU's as it would generate more expenses than profit.