Question / Help Encoding lag on a dedicated PC with an i7-6700K

[Swordstoo]

I have just setup a second PC with a capture card. The capture card is working perfectly and feeding video from my main system through with no load on the CPU. While idling with the capture card active, the system runs at less than 5% CPU. I'm trying to stream to Twitch.tv with these encoder settings:
Encoder: x264
Resolution: 1920x1080p
Frame rate: 60FPS
Rate control: CBR
Bitrate: 6,000
CPU Usage Preset: SuperFast. Keep in mind I have tried both SuperFast and VeryFast but they do not seen to make an impact on quality but SuperFast dropped less frames according to the log file.

I am running an i7-6700K and from what I've read should be plenty enough to run a 1080p/60FPS stream without quality issues.
Here is a small snippet of me testing Skyrim on these settings and running into extreme frame drops: https://clips.twitch.tv/SpeedyFrailFrogSSSsss
For context, here is the line in the log that is complaining about dropped frames:
"Video stopped, number of skipped frames due to encoding lag: 25857/164679 (15.7%)"
At the same time, OBS complains about the encoder being overloaded, but I do not understand why an i7-6700K is unable to stream at these qualities.
Another interesting piece of information is that OBS will use only about 50% of my CPU in task manager yet task manager reports 100% total CPU usage.This is strange considering it's a fresh install of Windows and everything in the list only adds up to 65% or so. The CPU is also staying well below 40c degrees on air cooling. A constant encoder should be increasing the temperature of the CPU in the 60s but it doesn't go above 40c.
If it matters, hyper threading is enabled and the CPU is not overclocked.

 

[Swordstoo]

For those that stumble upon this post in the future with issues running a 2 PC stream I will share what seemed to resolve my issue.
I noticed high CPU usage when streaming but the OBS software was only using 40-50% of CPU at any given time. I simply did everything I possibly could to alleviate load on the CPU. What ended up working was installing a 6 year old dedicated GPU that I had lying around (Any discreet card will take load off of internal graphics) and the system can now stream 1080p/60FPS with no issues at all! Recording to the local SSD and streaming to Twitch.tv are both smooth as butter. I swapped back to the very fast encoder preset and have yet to experience issues.

Tl;dr: Installing a GPU to take load off of the CPU's internal graphics effectively doubled my encoder throughput.. somehow.

 

[koala]

Since OBS needs GPU resources to composite the video stream, it's quite normal what you experienced. Onboard GPUs are usually very weak. They are sufficient for displaying the Windows desktop, but that's all. OBS needs a bit more. Even if it's only running on a pure streaming PC without game capture.

If you add an external GPU for OBS processing, make sure the external GPU is actually more powerful than the internal one - even in the field of external GPUs, there are many that are even less powerful than the integrated GPUs.

You can use benchmark websites like https://www.videocardbenchmark.net/ to compare the ratings of GPUs. If you want to stream full hd (1080p), you should have a GPU with a score of perhaps not less than 2000, better 2500. Internal GPUs have about 1000, only the most recent just reached about 2000. The Intel HD 530 in your i7-6700K has a score of 999. Better Gaming GPUs have scores above 6000, current good gaming GPUs have scores above 8000, current high end gaming GPUs have scores above 10000.