I have 2009 Mac Pro, which has been upgraded / flashed, running High Sierra. I'm currently using an unflashed GTX 1070, but I want to upgrade to Mojave. I'm not gaming on this Mac, but I do have a 3440 x 1440 monitor running at 100Hz, so the card needs to be strong enough to support that resolution and refresh rate. My questions are: 1. Can I upgrade from High Sierra to Mojave using my current GTX 1070? 2. Is there a reasonably priced video card that macOS supports natively, is Mojave compatible, and runs at PCIe 2.0 (offering boot screen)? I read about the Radeon RX 580, but I haven't seen any version of that card that is "Mac edition", offering PCIe 2.0 support and boot screen support.