SSD bottlenecking the encoding of a 1080p video ?

Hi,

I recently built a (very modest) editing/3d workstation pc:

ryzen 7 2700 (all cores overclocked to 4.1GHz)

32gb 3466MHz RAM

GTX 1650 Super 

m.2 SSD as system drive (MyDigitalSSD BPXP 256GB)

SATA SSD for various media (WD Blue 500GB)

Bottom line: I'm trying to encode a 1080p (H.264) video with a very low bitrate (0.4 MB/s) and a very low sound quality - It's a reccording of a 4-hour online class that I'm trimming down, and with these settings it is only expected to be around 900MB.

I set it to hardware encoding with 1 pass.

While encoding, my CPU usage is ~15%~ and GPU is ~55%~. 

Memory is at about 10GB usage (out of 32GB)

My SSD is writing at ~10 MB/s~

when I try software encoding the CPU constantly jumps between 20-80% and rendering time is 2x longer...

Is the SSD bottlenecking the system due to multiple small writes it can't handle?