Pellate

depends on many factor such as resolution and game's cpu usage
but most of the time, if u stream 1080p60 at 6000kbps, your cpu should be able to do medium without any dropped frames... in most games -glares at monster hunter world-
 
dropped frames only occur when the encoder is overloaded or your bandwidth to the streaming server is insufficient
neither cpu or nvenc encoder should have dropped frames.
but yes, the quality of nvenc turing is very good, compared to other solutions
older generation nvenc is slightly worse than software x264 fast preset in most cases, but still tons better than AMD encoder

rich.
well, it depends if you require all 12-cores then, no one knows your work requirements better than you do
well, you could say that you're probably have replaced them or is on the verge of replacing when they do break
unless your OC is insane

Strictly speaking there's no GPU that doesn't match with a CPU, is just that you should balance their relative power so that you utilise more of both at the same time
 
ie: (made up situation and number, not real number)
Rx 570 can run csgo at 40 fps
Rtx2070S can run csgo at 80fps
3900x can run csgo at 100 fps
 
Now if you pair the 3900x with 570, you'll get 40fps, and 60% of the CPU is not used, which is fine unless you'd like it to run better
 
If you pair 3900x with 2070S, the game will run at 80fps, only 20% of your CPU is not used, which is more balanced compared to the configuration before
 
u can swap the number and components around to signify different bottlenecks for different task
ie:
Rx 570 can run x at 40 fps
3900x can run x at 80fps
2070S can run x at 100 fps
 
rx570 would bottleneck a 3900x, but a 3900x would bottleneck a 2070s in this particular task
 
or
 
3900x can run y at 40 fps
570 can run y at 80fps
2070S can run y at 100 fps
 
3900x will bottleneck any of these gpu in this particular task
 
What do you mean?

Yes. It depends on the game.  There are a few very gpu intensive games where my 4770k might bottleneck a 2080ti. Reviewers don’t test those games because it’s pointless for them to use for reviewing. There is REAALY cpu intensive stuff where a 3900 wouldn’t bottleneck a 570.  Theyre generally not games though.  Linus Torvalds recently built a machine with a 3970x and a 580 and pointed out that for his use there was too much GPU. He only bought it because it was the cheapest gpu he could easily find.  He’s a programmer that compiles a lot though.  It’s all about use case.  The advantage of a 3900 is you can put more GPU on it later.  It will last through many GPU improvements and you can run very cpu intensive stuff and still force the gpu to run flat out.  A 3700x was mentioned earlier because that cpu has as many threads AND more ghz than any even soon to be released console has.  Anything written to run on a console can never bog it down because it’s too big.  A 3900x would have enough power to run any console game and do other stuff too at the same time without getting bogged down because it’s got 4/8 left over.  With a 3900x you wouldn’t need to buy an new cpu for many years.  That’s what I did many years ago. I bought the biggest cpu I could get. My machine has had 3 gpu replacements with no cpu replacements. It’s been many years though and my $400 cpu can be outclassed by stuff costing $100.  More importantly it’s only 4/8 so when the new games for the new consoles come out it probably won’t run new games well anymore.  I figure ive got till Black Friday to get something faster.  Not a bad run.  I’ve had that cpu for a long time.