GPU Upgrade advice

Upgrade Question
If we say the "budget max" is $1700-1800, and this could include upgrading to a Taichi motherboard:

_With a new motherboard_, no need to bifurcate
1. Would you add a second 5060Ti (16GB)? Someone is selling one for around $500 locally;
2. Buy a used 7900 XTX (24GB VRAM); local seller, $850

_All-in on the GPU_, I'd have to make the current motherboard work for my use-case
3. Or, just go for an R9700? (No budget for Motherboard upgrade)

Current system
- Ryzen 9 9950X edit: added after original publishing of post
- 96GB system RAM (DDR5)
- 5060Ti (16 GB VRAM)
- Llama Cpp but I built for CUDA; default Vulkan had issues, and the GPU would "disappear"
- ASRock X870 Pro (only 1 PCIe 5.0 x16)
- I could run a second card very slowly at x4
- Researching if I could bifurcate x8/x8 in the 5.0 slot

I bought this PC used as-is; I do contemplate upgrading the MoBo to an X870E Taichi for 2 fast PCIe lanes

The "largest" models I currently run
- Strata IQ3_S (just tried this yesterday, was impressed)
- RentedNoodle/Qwen3.8-27B-GSQ-RCO-IQ3_XXS-Uncensored

My most typical uses
- writing code
- analysing documents (PDFs)
- analysing maps and images

The idea is to use something like Headscale or Tailscale at some point so I can always access local LLM from laptop if I'm not home.

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Yes, I'm aware of "workstation" motherboards, CPUs, etc. and I'm not at a point right now where I want to take that path.