Question / Help OBS Poor NVENC Performance?

[KaJ]

Before I begin, here is my gaming machine setup:
· i7 2600k overclocked to 4.6ghz
· Nvidia GTX 980
· NVENC encoder, High Quality, 25000kbps, cbr, cbr padding, cfr, 1080p, 60 fps

And here is my streaming PC that has NGINX-rtmp setup and is functioning very well:
· Xeon E3 1241v3
· x264 medium @ 720p, 60fps, 3000kbps, cbr

So after using Shadowplay for a few months and being enamored by the <5% performance hit for local 25000kbps recordings, I decided to install nginx on my server to let it do the hard work.

Flow: Gaming PC / NVENC @ 25000kpbps -> NGINX Server / x264 @ 3000kbps -> Twitch

In theory it sounds great, no more performance issues when playing CPU intensive games and still getting the good quality using the x264 encoder. However, the OBS implementation using the NVENC encoder hits my FPS way too hard. Here are a few examples:
· The Division: No encoding = 101 fps Shadowplay = 98 fps, OBS NVENC = 74 fps, x264 veryfast = 73 fps
· 3dMark Firestorm score: No encoding = 11790, Shadowplay = 11680, OBS NVENC = 10300, x264 veryfast = 10200

So what gives? Why is the NVENC encoder hitting my performance as much as the x264 encoder? Why is it not more similar to Shadowplay?

 

[FerretBomb]

Official Shadowplay has a special proprietary back-end frame capture method that NVidia (in all their long-standing anti-competitive nature) has not seen fit to expose in the NVENC API.

I'm not sure that GameCap should be hitting QUITE that hard though.

Could you post a logfile from a testing session at least 5 minutes in length? If you're on OBS Studio, NVENC support just was added so it might be bugging (running both encoders, not actually switching over, or something like that). If you're on Classic... not sure. Would need to see the logfile to see if anything stands out.