The file '120mm CPU Heatsink Fan To 80mm Case Exhaust Duct 3D Printer Model' is (stl) file type, size is 1.7MB.
This is a duct that allows the CPU cooler fan to double as the case fan. The idea is to minimize the amount of noise caused by fans in a low-powered computer. This duct was designed to fit my particular CPU cooler (Cooler Master Hyper 212 Plus), motherboard (GIGABYTE GA-Z68A-D3H-B3), CPU (Intel i3-3225), and case (generic ATX mid-tower from ~2001). Therefore, it is highly unlikely to fit your configuration without modification. It is here more for inspiration. However, an Onshape link is provided if you want to see how it was designed and perhaps modify it for your configuration.
Onshape Link: https://cad.onshape.com/documents/5480b5d2c04a2cdc4541a164/w/32ac66a7730ef92440de29a0/e/19ae53cdc76abe089a12630b
Case_Fan_Duct_-_Duct.stl | 3.5MB |