What settings on Nvidia H.285 are equal to default x285 settings?

[ShadowWizard]

I am very new to the video encoding/editing/playing with world. I am trying to re-encode some very high quality videos in h.284 format to save some space. I have been using StaxRip. I have used the default settings on x285 and managed to get a 12 GB video down to 2 GB with no seeming loss of quality. I have also re-encoded several videos of the same type recorded with the same camera and gotten 3 GB files down to 7 or 800 megs. I am very pleased with the results using these default setting, but the issue is, it takes 3+ hours to re-encode 15 min of video. So I have started to play with the Nvidia H.265 re-encoding, and was VERY impressed with the speed, but the quality is crap. So basically I am asking, what settings do I change on the default Nvidia H.265 settings to make the quality match the default settings of just x265?
Thanks.

[poisondeathray]

Short answer is you can't .

One big reason is NVEnc HEVC/h.265 doesn't use b-frames, so the compression efficiency is much worse