I know SLI needs PCI Express x8, my motherboard has two PCI Express 3.0 x16 and 4 PCI Express 3.0 x1. I have the MSI Z370 Gaming Plus motherboard (https://www.bestbuy.com/site/msi-z370-gaming-plus-socket-lga1151-usb-3-1-gen-1-intel-motherboard/6169110.p?skuId=6169110). It doesn't say anywhere that it supports SLI, but it does say it supports CrossFire, I haven't tested it because I don't want to blow $450 on another 1070 and have the chance it might not work. If someone could help, that would be great, when I built my PC I didn't check if it supported SLI.