Gideon please feel free to DM me on this. But could you have you put me into contact with someone in your infrastructure team? If so let me know and I'll pass long my work email address. I'd love to hear about their pain points and big wins if they can share!
How underused, cool, etc. are the top CPUs these days if the system is GPU limited on a game?
what are you talking about? it all depends on what resolution you run at and unless you are running a real low end gpu, a better processor WILL always give you better frames. that's why they always use 9900k or 3900x for reviews to try and make sure the processor isn't holding the card back. Hell there are some games where i limit the gpu to a certain fps just to cut the load down on it so it isn't just wasting power and heating my room. but its nice to know that the power is still there if i need it for future games. Trust me you still want a good cpu for gaming. I mean, do you think your processor is suppose to be running 100% while your gaming? If it is you're definitely losing not only fps but your frame pacing is probaby sh!t. Hell I like my parts to stay cool anyway, besides they will last a lot longer like that too.
here's some good reading on the subject. https://www.techspot.com/article/1496-pairing-cpu-and-gpu-bottlenecking/
edit: lets do a for instance: for instance you built a system with the lowest end processor they used the pentium g5460 and the lowest end gpu they tested the 1060 and you were getting 50fps. sure with the 1060 you'd still be getting 50fps with a 9900k because you are gpu limited but lets say a year or two later you upgrade your card to a 1080 or 2080 with the low end processor you wouldn't see ANY boost in performance youd still be only getting 50fps!!! You'd be pissed you just spent $700 on a new video card and got 0 boost in performance. But if you would have built around a 9900k or 3800X and upgraded your gpu you'd see a massive boost. And with the new consoles coming out with 8 core zen 2 cpu's in them you are gonna start seeing games use a lot more cpu horsepower coming in the near future. so personally i wouldn't skimp out on cpu if i was doing a build. unless you plan on upgrading that too.
CPU is important and I can give an example. I loved through. I had a venerable 2600k CPU laird. With 16gb of ram on an msi mobo. I had gone trough three generations of video cards on that ending up at a 1070. In my game dejour at the time I was getting close to 100fps if I didn't limit it.
Eventually I upgraded. My CPU, disk and ram to what I have now a 7700k with 32 gig of ddr4 2666mhz and a msi motherboard and nvme drive. It literally doubled by fps with the same card.
Tomorrow my 3900k with another msi motherboard and 32 gig of ddr4 3400mhz ram should arrive. I am expecting better performance out of it and increases gpu performance even if I frame cap. I've noticed my game now doesn't like to work well if I am in a browser. And I'm hitting close to 60% utilization across all cores.