It is not true at all. In my work a few colleagues have one board like this one and with the adrenaline driver 17.11.1 of november 2017 it is working well with 11 amd graphic cards. For the hashrate just switch to compute mode from your radeon settings and the hashrate of a rx 580 is 31.6 mhs same as with blockchain drivers.
I actually prefer the new driver, much better than blockchain driver however nothing like the old amd drivers + wattool, right now you have to change the voltage within the bios which is bad, with old amd drivers + wattool we could change voltage on the fly regardless which voltage was in the bios. Removing voltage on the fly is regressing on progress. Yes you can change using afterburner but afterburner is bad for that and there is no other tool like wattool was.
