Yeah, I know. I tried them with 1 miner per EVGA psu, plus the third on an old Corsair TX750. Still no luck overclocking. I am using a Kill a Watt, and am measuring 1080W at the wall at stock speeds. The max it ever hit was 1150W when trying to overclock.
Well how are you going to overclock 3 S3's with 2 power supplies that can't supply enough current to do it??
Each S3 at 250 will draw 400+ watts.
I would connect just 1 or 2 and try to overclock them 243 and 250. if they work then it is what I noted, the power supplies cant supply the amps needed for 3 overclocked