NV GTX1070，使用DP口输出，启动加载完UEFI前无输出，可尝试方案如下，也可能适用于DP1.2无输出：
https://www.nvidia.com/en-us/drivers/nv-uefi-update-x64/
RELEASE HIGHLIGHTS To enable the latest DisplayPort 1.3 / 1.4 features, your graphics card may require a firmware update.
Without the update, systems that are connected to a DisplayPort 1.3 / 1.4 monitor could experience blank screens on boot until the OS loads, or could experience a hang on boot.
The NVIDIA Firmware Updater will detect whether the firmware update is needed, and if needed, will give the user the option to update it.