According to MacVidCards.com, one must use a modified ROM on a stock PC video card to get it to use the PCIe 2.0 spec vs the PCIe 1.0 spec when installed on a Mac Pro.
A MacRumors post suggests that it is not necessary to use a "flashed" ROM on an NVIDIA 10XX card if using the web drivers as it will work in PCIe 2.0 mode without being flashed, but Windows will only work in PCIe 1.0.
I want to buy a GTX 10XX to upgrade an old, but nice Mac Pro 2009 model I have. I don't want to spend $700 or more on a "flashed" GTX 10XX if I can get the same performance using a same make and model non-flashed GTX 10XX.
While it would be nice to get PCIe 2.0 bandwidth in both Windows and macOS, I'll be spending most of my time in macOS.
Is it true that macOS will utilize PCIe 2.0 bandwidth using NVIDIA web drivers for a GTX 10XX GPU without being flashed?
Best Answer
It appears that a standard GTX 1070 Founders Edition uses a link speed of 2.5 GT/s (PCIe 1.0) even with the latest NVIDIA Web Drivers:
The GT 120 I have sitting next to it has a 5 GT/s link speed (PCIe 2.0):
So I guess that answers my question.