the risk is very high right now, GPU mining lives on 3 families of algos mainly, cryptonight, equihash and ethhash.

ASICs are about to take over equihash,
ASICS partially took over cryptonight, FPGA is threatening to clean out the rest of cryptonight (if successful)
I still laugh at the POS threat to ETH, but that's a different topic. With most GPU miners forced in to ETH, profitability will be bad for a while. and if you believe in POS for Eth, then ETH will be completely dead.

Running a gaming rig and mining rig on the same is a terrible idea. 6 rx580's will raise your room temps by 3-5 degrees F in a normal sized room with no additional ventilation. Also mining machines tend to feel a bit sluggish when mining, no way i would be firing up a first person shooter while mining. you could browse and mine just fine though.

Also remember that a normal room breaker is only 20 amps, which is only 1800 watts or so.

If i was to get in to mining right now, it'd be to sit back and watch fpga status and then decide. ASIC has already played their cards, if FPGA's area real (not talking about the $4k solutions but the ones that are sub $1k), then GPU's are screwed for a while.