Hi. I recently installed High Sierra on my Z170-XP SLI based system and have everything working except the GT 640 graphics are quite choppy. Things like opening notification center and launchpad lag. I have full QE/QI support or whatever. I'd assume since this is a natively supported card I don't need any web drivers. Using iMac14,2 SMBIOS. If it matters I'm using a 20in Cinema Display (the old one) on DVI and a Samsung off the HDMI output with an HDMI to DVI adapter. I've attached my EFI folder if you need it. This card was moved from my 2008 Mac Pro running El Capitan and it worked just fine on there. Thanks.