The RTX 3090 BFGPU Founders Edition is a 3-slot graphics card and measures 313mm in length and 138mm in width. You will need to check if your system's casing or chassis can accommodate it. RTX 3090 from AIB partners are also expected to be big and will occupy 3 slots. It's also not advisable to install these graphics cards inside a closed-case system, where air-flow is restricted since it is not a blower-type cooler.