u/K_Zero_BL2

What's the difference between the different 5090's i see online? Because i see one that's like 2700$ and another that is 4000$. I try to research but i never get a straight answer about what makes them so different, or if i do get an answer it doesn't explain it in terms i know because i'm new to pc building. So if anyone can give me an answer that i'll understand that'll be very helpful thanks