To start, I'm new to mining.  Put the rig below together in Dec '17 and after reading a thousand forums here and reloading everything 10 times over several weeks I have a stable rig.  

I have been mining XMR with this setup on Minergate for a few weeks fairly stable.  Cards are averaging 600 h/s (3.6 k/h total for 6 cards).  This sounds on par with what I read for stock bios cards mining these algorithms.  I decided to see what the cards would do mining ETH and I'm only getting ~11 - 12 mh/s per card (~70 mh/s for 6 cards).  I see a couple mentions of this issue on forums but haven't run into anyone who has solved it.  Any Ideas!?!?  Thanks!!

Update:  Same rig runs ~25 mh/S on claymore.  Minergate seems to show exactly half the hashrate on their dashboard.  Funny thing is I feel like I accumulate Eth faster on Minergate despite the hashrate shown...    

MSI Z270 SLI Plus (4g / gen 2)
8GB Ram
64G SSD
Cely i3 3900
3x Sapphire Pulse 580 8g (No Mods)
3x XFS 580 8G (No Mods)
2x 750w PSU (3 cards / 3 cards + Mobo)
Windows 10 Home (UEFI)
AMD Crimson Beta Driver (No Compute Setting Available)

I registered here just to hear how someone got more than 4 gpu's running on the z270 sli plus, let alone 8!!  I read somewhere that the number of pcie lanes only supported 4 gpu's, I landed here looking for info on the m.2 ports hoping they had dedicated lanes and I could get 6 cards running.  These mobo's are a pain in the ass from what I have experienced and read.  

Here's what I got;

Z270 sli plus
I3 3900
8gb ddr4 2400 mhz
64g ssd
3x Sapphire rx 580 pulse
3x xfr rx 580
2x 750w psu's
Windows 10 home 64b

Here's what I have running 4 cards:

4g enabled
Gen 1
96 bus clocks
Pcie power saving off
Windows 7 something... (support?)  disabled in bios
Virtual memory 20g ish
Tested risers 1 x 1
Installed cards 1 at a time
Mixed drivers crimson + latest version
Latest bios flash
Windows and drivers updated

I'm no computer or crypto expert, wouldn't have known what most of the above meant 2 months ago.  The best thing the sli plus has done for me is make me learn about all this stuff!!  Any help would be appreciated!!