On the 1080ti I run gemma4:e4b to to do RAG and vision jobs. Not sure the quants and I just run it in Ollama that auto adjust the model because I'm lazy. Not 100% sure but I think mixture of experts load the parts that are needed so there easier on memory. Offloading to CPU memory or swap is a big performance hit.

I tried to run a 300b model on the main PC once, but it took half an hour to get a few words out of it. You can go past the VRAM on the card but sacrifice speed.

Probably not, or if it runs it may take hours or days to get a full output. VRAM on the GPU really decides what will run reasonably. Try an 8 billion parameter phone sized model and see if its faster than sending a letter, then keep moving up until your setup can't handle it.

8B models are a bit too dumb to use any tools reliably but should handle a basic conversation.
llama cpp will allow you to manually load a model and tweak settings.

unsloth will give you a basic setup with some tools, manage model downloads, and settings.