Occurred with different codecs (video: NVENC H.264, x264vfw; audio: PCM).
BTW according to:
Re: caching on the disk
Solution for slow hard disk
And my experience in recordings of extremely high data rate:
My HDD is capable of sequential write of 220 MB/s, while it starts to encounter I/O bottleneck at around 95 MB/s (no problem with a SSD), likely due to non-sequential writing caused by insufficient caching.
It appeared of necessity to allow the user to explicitly set the amount of memory allocated for caching.
And perhaps this page needs revision according to Re: caching on the disk. (for disambiguation)
Enable write caching on the disk: If you check this option, Bandicam caches the data while recording. If you uncheck this option, Bandicam saves the data directly while recording.