I've been meaning to buy an RX 580 but I don't have enough to buy a PSU with an 8-pin, so I was thinking of purchasing an adapter instead. But here's my problem, I don't know how much watts they pull from my PSU. I'm not sure if the adapter would add more watt consumption from the PSU on top of the GPU's. I have a 600w PSU and an i7-2600. Ask more details if some are lacking. Thanks!