using CCminer under linux 4.12.4, Nvidia drivers 384.59
One card shows 456 MH/s, the other shows only 379 MH/s while mining LYBR (but I do have this problem with any other coin), both cards are Galax EXOC 1080TI, both connected directly to the motherboard, no raisers. No overclocking on any, no SLI, the only difference is that one of them is connected to a monitor right now, the other is not.
Any tips on how to approach this?
Don't know how I missed it that you are on linux
try setting the mobo bios to run the monitor off the mobo.
other ideas try using nvoc 1018 os from novac
it allows for a full linux version and mining just use a good usb stick like this
http://www.ebay.com/itm/Lexar-64GB-JumpDrive-P20-USB-3-0-Flash-Drive-Speed-Up-to-400MB-s-LJDP20-64GCRB/381906408887?you can set clocks for each gpu so if one gpu needs a bit more clock it would work.
https://bitcointalk.org/index.php?topic=1854250.0