You can use ShadowPlay. I'm using ShadowPlay for last 2 years on my youtube channel which is primary income. You can try using manual recording, 1080p60fps, 30k bitrate. Why 30k ? Because you want to re-render that quality in Adobe Premiere/Vegas to add watermark, edit scenes etc.
If you want to use facecam, I recommend using OBS software, set recording resolution to something like 640x480 or even less (calculate in photoshop what size is camera and record in that resolution), since once when you record yourself you just add that in upper track in rendering software and viola, you have facecam.
Now..ShadowPlay will not use more then 1-2fps, OBS you are recording on purpose in very small resolution (with let's say 3000 bitrate) and because of that that will not even be noticable when you are recording.
Cons for not using good quality capture card in this case might be.. You need to render your video and add separated facecam on upper track in render software, and you need to sync camera and your commentary to go along with game (which takes from me approx 2mins of work once when you get your habbit of using hotkeys properly). For example you put on Numpad5 both OBS and ShadowPlay to start recordings..so you have synced without need to move couple mm left or right on track to sync your lips with commentary.
I also use Audacity for crystal clear mic quality on 15$ headphones.
So it's possible. Quality will stay more then good, believe me.
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