I thiink on Z77 I had max Pci e 1.1 with Celeron and hd 6870. But on Z170 all RX are runing on 3.0 and 006 ver . eitherway, 1.0 is more than enough for mining cards. For Acron, not sure, didnt pay attention.
I have 4 or 5 z170 boards from biostar https://www.amazon.com/Biostar-RACING-Z170GT7-Intel-Motherboard/dp/B06XDKHN1S
I think that these boards with the nest x2g and acorn 215+ will be true beasts
This board may do four four card nests. 16 x 15 = 240 watts
16 x 15 = 240 hash
That is like 12 1080tis which would use over 2000 watts
Costly as 16 x 330 = 5k and 520 for nests total of 5500