Question / Help I am having encoding issues despite low (30-40%) CPU usage

[Duncan Gannicott]

I started streaming Rainbow Six: Siege with high video settings and high stream settings and bitrate (1920x1080 and 3200 bitrate I think) and immediately had encoding issues despite only using roughly 40% of my CPU. I proceeded to tweak and scale back stream settings to 1080x720 output with a 2500 bitrate and lowered my in game video settings and still found I was having encoding issues despite having even lower CPU usage then before. I have attached a log file from my broadcast so hopefully someone knowledgeable can point something out. I'm new to this so if there are any big things I'm not seeing I apologize but I would really appreciate the help.

My system specs are:
MSI Z97 PC Mate LGA 1150 Motherboard
Intel 4790K 4.0 Ghz Processor
EVGA GeForce GTX 960 4GB Graphics Card
Seagate 2TB NAS HDD (64mb Cache and 6GB/s) Hard Drive
Rosewill ARC Series 650W Power Supply
2x8GB G.SKILL Ares Series DDR3 Ram
Logitech HD C920 Webcam
Windows 8.1 OS

 

[xxAssassin349]

Output 'adv_stream': Number of skipped frames due to encoding lag: 870 (5.6%)
Output 'adv_stream': Number of lagged frames due to rendering lag/stalls: 781 (5.0%)

Your CPU and GPU are both overloaded. For your CPU, you should decrease the FPS to 30 and use a faster x264 preset. Ideally, you should use the slowest preset that doesn't give you high encoding warnings (start at veryfast and work your way up or down, depending on what your CPU can handle). For your GPU, decrease in-game settings, cap your in-game frame rate (VSync), or use other ways to reduce GPU usage.

 

[Duncan Gannicott]

Thanks for the tips, what I am specifically wondering is why my CPU Usage can be so low when I monitor it and yet I still have encoding issues and need to downscale. Is OBS bottle-necking? can it not use all of the threads or cores my CPU offers to its fullest extent or is it using the same cores or threads as the game I am running which bogs down recording? I understand my GPU becoming overloaded since I did not go for a top of the line graphics card in my build but I put a good chunk of money into a nice processor in hopes of not having issues like this. It seems like I should be able to get more out of my processor as far as recording goes but maybe that expectation is unrealistic.