Thanks! I'll be hooking up the H110 soon.
I'm using USB 3.0 PCI-E 1x to 16x Powered Extender Riser. Version 006C. And they are 6pin powered. Edit: I don't use the crappy sata converter.
VERY good call.
The original ASRock "BTC mining" motherboard design predates widespread use of powered risers - the current R2.0 version does not, but seems to have stuck with the molex on the motherboard design for backwards compatability, then they carried it into their 13-slot version.
ASUS does the same thing on their 19-slot B250 BTC Pro design - but the board works fine without the molex if you use all powered risers.