A Graphics Card that is a part of Nvidia's Geforce RTX 30 series video card line. It is the successor of Nvidia's Titan developer line of video cards.
The RTX 3090 is a relatively large graphics card and generally takes up at least 3 expansion slots within a computer. The founder's edition (a line of video cards produced and sold by Nvidia themselves) version of the RTX 3090 features two cooling fans, one of which is an uncommon pass-through fan that vents the air from one side of the card to the opposite side.