I would also like some PC build advice (workstation build)

Hi all. I'm working on an idea for my next desktop/workstation build since I stumbled into some resources that make something more awesome than what I currently have a reasonable option.

What I want to use (because I already have these and thus can save money - got a bunch of rackmount computers at auction and got pretty lucky): infinite sticks of 16GB DDR4 3200 (ok, so I have 20 sticks left after selling a bunch, not exactly infinite but good enough for wanting a single maxed-out build) and 4 RTX A4000 16GB cards. Probably I only intend to use 2 of those and sell the other 2. I also am spoiled for options with various 4U rackmount server cases and a couple of them have 1,000W power supplies (the 2 computers that each had 2x A4000 cards had 1kW power supplies).

My current desktop is an i9-11900k / 64GB DDR4 3200 / RTX A2000 6GB. At first I was interested in just popping a couple of the A4000 cards in but then research banged my head into the issue of PCIe lanes being limited by the CPU.

Options I'm currently considering are Threadripper Xen 3 generation (since that uses DDR4 3200, lets me use 8 sticks depending on motherboard, and gives me 128 PCIe 4.0 lanes), EPYC of some variety since some of those also fit into the 'can use tons of RAM and have tons of memory channels + more than enough PCIe lanes' or..... dual Xeon? AMD seems like the better choice though - but correct me if I'm missing something there.

If I've missed any other options that would give me enough PCIe lanes for at least 2 A4000 cards both connected at full PCIe 4.0x16 and the ability to utilize as much of the RAM as I have (and have the advantage of more memory channels than standard desktop processors) please let me know.

Also looking to not break the bank too much, something that fits into the sub-$2K range, or close to that, would be preferable (and cheaper being more preferable). Anything that goes past $3.5K is almost certainly not up for consideration.

Last point of consideration is that I'm not looking for any part of the new build to be less capable than what I already have, and am not looking to spend significant money for a non-significant capability increase.

Use-cases relevant to my desire for the horsepower: video rendering with Blender (I certainly wouldn't mind rendering going a lot faster when outputting H.265 or rendering hour+ videos), and dipping my toes into local AI (have been interested in this but until I lucked into the A4000 cards it wasn't really possible. With a couple A4000 cards I should be able to run some of the lighter-weight models, at least I believe so (I have, as of yet, no experience running local AI). Would be running Linux (I currently use Linux Mint). Gaming is an afterthought and I don't play anything AAA / ultra-high graphics. Mostly for gaming I just enjoy playing Magic: The Gathering Arena as I drink my morning coffee, so no major hardware requirements there.

Thoughts?

Edit: the DDR4 3200 is non-ECC RAM.