Mac Pro Windows PCIe bus speed

When i'm in windows 10 (bootcamp) my GTX 1050Ti seems to be running at PCIe 1.1 when the card supports PCIe 3.0 speeds. When i'm in mac, it looks like it works fine. am I missing something? I read somewhere that it runs at full PCIe speeds in mac but when in windows or linux it runs at a slower speed but I can't seem to find that page anymore and now i'm confused. I only use windows to play one or two Windows only Games and they're demanding of the full bus speeds. I would use mac for everything but those two games don't have a mac port and probably won't any time soon. I have a Mac Pro 5,1 and I run Windows 10 on a separate hard drive from my El Capitan / High Sierra install. any help would be appreciated; Thanks.