How do I maximise GPU/CPU usage when converting to x264?

[daklone]

I'm currently using Handbrake's GUI queue to convert some video to x264 in serial fashion and would like to know if anyone has any tips on maximising GPU/CPU usage to reducing encoding time and/or a way to parallel process?

I've been using NVEnc in order to utilise my GPU for conversion, but it only ever seems to register about 10% video encoding usage. I also have an Intel HD 4600 GPU available that supports IntelQSV (currently doing nothing at all) and my i7-4790K shows maybe 20% utilisation. I generally have about 25GB of memory available.

I'd really like to make much better use of my available resources.

[FPGA]

Keep in mind that encoding on a GPU is fast, but does not offer the best possible quality, compared to a good software-encode.
In handbrake, you could turn on igpu for decoding, it might give you a boost and max out your nevnc pipeline.
You could also try to decode on your nvidia gpu - one very easy way would be to use as-video converter - which gave me the best overall speeds without much configuration to be done when dealing with hardware-encoders and decoders, and also do simple and powerful batch encodes.
Staxrip and hybrid can also be configured to decode and encode on GPUs.