I'm currently running a custom desktop that I primarily built for Blender and gaming back in 2021. While it wasn't the ideal time to build, I was able to scrounge together some decent parts, including a used GTX 980. I actually have an old build video
here that goes over a bunch of it in more detail.
This spring I got tired of trying to cram all my textures into 4gb of Vram, so I broke down and bought a GTX Titan. While it doesn't have any of the cool raytracing or encoding features on the RTX cards, it is super powerful and can take tons of texture data with its 12gb of Vram. Right now I'd say it's probably the biggest bang for the buck used GPU for content creation, since its usually around $200.
Current full specs are:
CPU: Ryzen 5 3600
GPU: GTX Titan XP
MOBO: Asrock B450 Steel Legend
RAM: 16GB Oloy Warhawk (2x8 sticks)
SSD: 2TB Samsung Evo
HDD: 2TB WD Blue
PSU: EVGA 600BR
CASE: Phanteks P360
I'm also running a cheap firewire card that allows me to connect a Presonus Firebox for my primary audio driver. it's fine, the interface has a lot of I/O, but stutters a lot and sometimes doesn't connect on boot. The mic preamps are also really quiet, I wish I hadn't sold my Scarlett 2i2!
Right now I'm pretty happy with my whole setup minus the audio interface, I probably won't change anything for a while, unless another Titan falls into my hands!