OBS has very advanced features for enabling the NVENC chip on Nvidia cards but they haven’t enabled the HEVC encoding for good reason:
IT CRASHES THE DISPLAY DRIVER.
Try it yourself. Try to use the hevc_nvenc encoder in a custom FFmpeg output in OBS and try to stop the recording after starting it. (if you can find the right arguments to get it successfully started) YOUR WHOLE DISPLAY DRIVER WILL CRASH, ALL THE TIME, EVERYTIME.
While HEVC is an awesome codec for 4K 60p and above, and Nvidia GPUs of recent have the capability to use it, only stuff not using FFmpeg like Elgato’s dedicated capture utilities are stable enough to use it for something like their new Game Capture 4K60.
Sorry OBS fans. We’re limited to NVENC H.264 if we want to encode 4K 60p and you don’t have a CPU as powerful as Threadripper for x264. Also, protip, the only functioning way to record 4K 60p in H.264 NVENC is to choose “High” profile, leave the Level on “auto” and use a bitrate of 150mbps with 2 GPUs. One dedicated to OBS and NVENC, and one being the primary rendering GPU for the game. Bitrates above 100Mbps will NOT UNLOCK if you choose a manual Level selection, say Level 5.1. This is the weirdest thing about the NVENC encoder I have discovered to date.