Go with the i9-9900k ;)!
I don't have the 2080TI I have the 2080, but man that paired with 32GB of RAM is just a beast.

The i9-9900k has a nice price.
Right now I'm running a EVGA 2080 Ti Ultra Hybrid on a EVGA X299 FTW K motherboard with a i9 7900X cpu and 32 GB ram (Corsair Vengeance RGB PRO 3000 MHz (XP profile)).
So I'm slowly building a X299 system (due to the expense).
So far I have a EVGA X299 Dark motherboard (I bought the 10 warranty and the the EVGA Z390 DARK was not available at the time, not in production).
EVGA 1600W T2 power supply.
Corsair Vengeance RGB PRO 4x16 2666 MHz ram (the manual said that is the preferred memory speed).
So, still deciding on cpu.
I have a EVGA 2080 Ti Ultra air cooled (bought that before EVGA 2080 Ti Ultra Hybrid came out) and the EVGA water block for it (but not installed) in another computer that I'll be using.
I'll install it on my Praxis wetbench and fit the EKWB EK-KIT X360 for the system until I can decide a case for it.
 
 
 

I'm using my computers for crunching SETI at HOME and I know that some of you are crunching FOLDING at HOME.
This is my dilemma, I want to create the most efficient desktop computer to do this.
 
Right now I'm running a EVGA 2080 Ti Ultra Hybrid on a EVGA X299 FTW K motherboard with a i9 7900X cpu and 32 GB ram (Corsair Vengeance RGB PRO 3000 MHz (XP profile)).
I also am running a x99 FTW K with a EVGA 2080 Ti Ultra air cooled but using a i7 6850k ( which also serves as my PLEX media server) with Corsair Vengeance RGB PRO 4x8 GB memory.
I also have a EVGA x99 Classified with a Broadwell-E 6950x cpu and Corsair Dominator Platinum 4x8 GB memory with a EVGA GTX 1080 FTW3 video card.
My new build is a AMD Rysen 2600x with a EVGA GTX 1080 Hybrid and Corsair Vengeance RGB PRO 4x8 GB memory.

So I'm slowly building a X299 system (due to the expense).
So far I have a EVGA X299 Dark motherboard (I bought the 10 warranty and the the EVGA Z390 DARK was not available at the time, not in production).
EVGA 1600W T2 power supply.
Corsair Vengeance RGB PRO 4x16 2666 MHz ram (the manual said that is the preferred memory speed).
So, still deciding on cpu.
I have a EVGA 2080 Ti Ultra air cooled (bought that before EVGA 2080 Ti Ultra Hybrid came out) and the EVGA water block for it (but not installed) in another computer that I'll be using.
I'll install it on my Praxis wetbench and fit the EKWB EK-KIT X360 for the system until I can decide a case for it.
 
Any suggestions would be helpful (BTW, I've been crunching SETI since 2002!!).
 
My stats:
https://setiathome.berkeley.edu/home.php
 

RainStryke
Since you all ready have a Ryzen set-up, I would suggest waiting for the Ryzen 9 3950X. From what i'm seeing, it looks like this is going to rival the i9 9960X for half the price.

With your current hardware, your biggest upgrade would actually be faster memory all around. Unless you are utilizing over 32GB, I would actually recommend dropping down to a 32GB kit with a much faster speed like 3600MHz. The X299 Dark supports up 4133MHz XMP RAM. It's really easy to set-up, it's usually just a matter of enabling XMP (Extreme Memory Profile) and having it do all of the leg work on the overclocking piece.
 
After researching the RAM support for that board, it looks like EVGA just kind of left it behind after updating it for the 9th gen stuff. The RAM support list on that board is pretty slim, so I would make sure to check up on that before making your purchase.

Click on your motherboard model here:
https://www.evga.com/support/motherboard/

+1. I would say the Ryzen 9 3950X with 16 cores is your best bang for buck

Hoggle
Depends on the game. Some are more effective with raw GHz speed while others are better with more physical cores even if those cores are running at a slower speed.

+1. This is why the best of the hardware reviewers choose 10-20 games when they review a product. 

more cpu sockets can feed multiple cards.
However, to feed one GPU you only need 1 socket and 4 cores - provided you have enough lanes left for your card.