I have your specs and can max most settings and get smooth playback. I'd check a couple of things...as mentioned above, make sure you don't have other software running in the background or at startup that might be clogging performance (check config.sys, try a clean startup).
Is this a VR flight? If so which brand? Things like Asynchronous Reprojection (Vive) settings can cause stutter. Try setting back to factory defaults. Google VR Jutter / Stutter for a lot of suggestions.
Check your BIOS and make sure you have the right optimized settings. A power glitch can sometimes change things. I had an issue once with memory running the wrong clock speed that caused stuttering. If you're overclocked, try stock speeds.