I have a used 3090 on the way that I got for 650€ shipped.

Can I use the 3090 and the 3080 at the same time?

I’ve seen many 2x3090’s here but not 3080+3090. I have a Gigabyte x570 elite motherboard so 2x16 slots though the second one runs at pcie 3.0 I believe. I also have an AMD 5950x and 32GB Ram at 3200Mhz. Would selling the 3080 and getting another 3090 be best? Or getting more Ram?

My plan is to run the best possible local llm, I’m really impressed with some results matching gpt4 level.