Im also mining in texas... and I have 0 AC costs. Running my cards in the garage yields ~5c higher temps than running them inside, only added cost is my 4 box fans @ 75w each. My 4 rigs @8.5c/KwH are using ~5.25 in cost per day, while putting out ~2.5g/hash. Each rig is pulling down around 500-750W, Unclocking the memory to ~340 helped cut the machine usage by almost 100W per box.