Have spent quite a bit of time with mine, I've gone through the whole unit software / hardware wise and made quite a few hardware notes that ill curate and share at a later date.

Voltage control is whack on these, needs custom firmware. Over the past few days of testing i was getting the following.

600mhz, 80C, 10K+ HW errors
581mhz, 55C, 5 HW errors
575mhz, 70C, 7K+ HW errors

How reducing clock speed results in more heat + HW errors is beyond me unless there are serious voltage calculation issues with these things. Also the CPU on the control board is running near full tilt just to keep up with the UART activity on the hashing boards. So even the simple act of refreshing the web page can give you HW errors. These aren't real errors, but just the control board lagging behind.

Also these are identical to the D3 in almost every way. pic firmware, eeprom images, etc... are all identical. The only thing that sets this apart from a D3 is the ASIC's, but considering it has all the same issues that the D3 had it makes me wonder if bitmain has come up with a more universal ASIC chip that can be reconfigured. There are JTAG headers on the hash boards, so who knows?