Hello all! Here's some background: Just set up Windows 8 Pro on my Late 2012 iMac with Core i7 and GTX 680MX using native EFI (not Boot Camp). I installed the latest Boot Camp driver package, and everything works well. However, I have issues when I update my NVIDIA drivers. The Boot Camp package comes with driver version 306.37. It seems to work fine. I'd like to update them, since I do a lot of gaming, though. Installation of new drivers works fine until reboot. Upon reboot, the Windows boot splash screen appears as normal. Following the boot splash, I am presented with a black screen. The iMac's screen backlight is still active, however. After a little bit, the backlight will dim slightly, and eventually turn off. After a few seconds, the system will reboot. This will happen a second time, then. Upon the third boot, Windows informs me that it cannot start. I am then able to boot into Safe Mode and uninstall the NVIDIA display driver, which then allows me to boot back into Windows. While in Safe Mode, I checked events and saw that the computer actually had a BSOD 0x116, which is a Video_TDR_Error. I attempted to install the Windows 8.1 update last night, and that failed as well. It gave error 0xC1900101 -- 0x4000D. It had similar behavior when it booted up into 8.1, and I found NVIDIA drivers in the update, so I suspect it's installing newer drivers that are causing the 0x116 BSOD. I sent an email to NVIDIA's driver feedback, but in the meantime I'd really like to get Windows 8.1 installed / drivers updated. Has anyone had any luck updating NVIDIA drivers on a similar setup, namely with EFI rather than Boot Camp? Any advice I should try to get this to work? Thanks in advance for any help or comments! TL;DR: Late 2012 iMac, GTX 680MX, EFI Boot. Updating NVIDIA drivers causes black screen at boot, uninstalling the updates is the only way to fix it. Windows 8.1 update appears to include updated NVIDIA drivers, so Windows 8.1 installation fails.