Probably the PSU. My crap Gold Raidmax bring the error rate to 0.3% at 393.75mhz and the hashrate is very low, like 1.23TH/s. My corsair does 0.01% HW and 1.27/TH/s. My EVGA g2 and platinium server PSU does 0HW and 1.3TH/s.
I also have one S5 that does 400Mhz 0HW and 1.32TH/s.
Nice....
Can you recommend the EVGA G2 for overclocked Antminer? Thinking that it would be nice to get 400-500 MHz without HW errors......
EVGA G2/GS, P2 too but its pretty expensive. (Not G1)
Most Seasonic PSU's, Seasonic OEM, superflower OEM. I dont think you can do 408-500Mhz without overvolting, which you would need to do at the PSU. So you would need to get something else.
I don't even know why one of my miners take 400mhz. Logically this means the chip voltage is higher, but i'm not feeding it any current any higher than 12.0X~ I also don't know if there is a danger to raising the voltage too high, aside from more heat. Maybe RichBC can answer that one.