advice please

It's a pretty good looking build for what you want it to do, but I think you could do a little better bang-for-buck. The extra oomph from the top proc just isn't there at all for gaming. The 12700 is overkill, and will be strong throughout the life of this rig. Save $230 there.

https://cpu.userbenchmark.com/Compare/Intel-Core-i9-12900K-vs-Intel-Core-i7-12700K/4118vs4119

The storage is very light, so I assume you have some you'll migrate over? The 970 EVO PLUS is a fine NVMe SSD, but it's a PCIe gen 3 part. The 1TB 980 PRO is one of the faster NVMe gen 4 SSDs and over doubles the speed of your pick. For $42, it's the right choice.

The next observation is one you may reject out of hand, but I think it deserves some consideration. The 3080 GPU is a good pick NOW for 4K, buy you're not running 4K. We are somewhere around 5 months from release of the next Nvidia generation, which are thought to promise another quantum leap forward. Faster, more cores at every level, performance from, say, a 4070, that will rival (or even exceed) the 3080, but bring large improvement in ray tracing and DLSS capabilities, as well as memory management. My suggestion is you consider the more than adequate performance of a 3060 Ti at 1440p, and save $505 toward a much better card all-around, and likely at better pricing for when you step up. A bit of a gamble perhaps, but the 3060 Ti performs on par with a 2080 SUPER due to it's overall improvements:

https://gpu.userbenchmark.com/Compare/Nvidia-RTX-3060-Ti-vs-Nvidia-RTX-2080S-Super/4090vs4050

Here it is stacked against a 3080:

https://gpu.userbenchmark.com/Compare/Nvidia-RTX-3080-vs-Nvidia-RTX-3060-Ti/4080vs4090

Does that look like $505 worth of difference? My build comes in at $2862, with almost $700 set aside for a new card when you think it's time.

Just for you to think over.   

You are most welcome, Jim.

I don't think a PSU upgrade will be necessary. My understanding is that they are working diligently to reduce power needs as we speak, and I know that lesser cards will rival the more powerful ones that are out now. Unless you are aiming for an overkill super system when you transition to 4K, I think the coming 4070 will probably be the right card for most. If not, the 4080 will be killer. You should have about 350W of overhead available in your system plus the 200W the 3060 Ti draws at peak, and my opinion is that will be quite enough. Worst case is you have to replace the PSU at some point, but the 850W is MODULAR, which means you only have to unplug and re-plug the labeled cables to the PSU itself. No re-wiring everything.

Custom fans may be designed on purpose to be a tiny bit quieter to justify the premium price, but it will not be noticeable. I've had three DS systems with stock fans, and they don't make noise. What does from time to time under heavy load are the radiator fans and/or the GPU fans. If you keep those fans clean regularly, even that will be a rare occurrence.   

You should ask DS to see if they can add a Corsair Commander Pro to your system. It's a fan controller that is great for adjusting fan speeds based on the temperature. I have that in my Velox, and I love it! My fans run at 800 RPM until the temperature reaches 70C. Then they ramp up to full speed if the temperature reaches 80C. Fortunately, the temperature almost never exceeds 70C, so the fans are nice and quiet nearly 100% of the time.