I read through this and i am confused to why the word "hardware" came into play. I use professional grade hardware and have found myself with variable frame rate.
There is only the software which is an issue, but there is no video game recording software that supports a constant frame rate. I use OBS, Raptr and Fraps and they are free, i have previously been a subscriber of Xsplit at $25 a quater and is used by leading companies.
I am a game developer and need to use it to share ideas and bought into the full Adobe CC package and expected it to work with all video software. When I last looked at this software it was £3,000, I don't expect to have any issues with this level of software.this
I see where the error lies though because the video fluctuates from 90-150 fps. Unfortunately it is hard to control the games FPS when your recording when your V sync is to a 200hz monitor and not 60hz.
My hardware by the way is
i7 5820k @ 4.1Ghz
16GB DDR4 2600Mhz
Crossfire R9 290 4GB OC 1100mhz
2 x SSD 512gb RAID 0
4TB Nas Back up