With 880mV i get a little over 42GH/s. Doesn't seem to get too hot on any part, which is nice. I suppose the --hexminer-option is like 16:540? I'll tune it more tomorrow, for now i'l just let it mine.
Yes that is correct. Try it with 900 mV if you want of course for 45 gh
900mV and freq 540 got me nearly 47GH/s

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I wish my original Bitfury H-boards would go this far, but the regulator is not up to the task. One does over 40G with 0.84V but speed tanks soon when regulator overloads...