These drivers are labelled for windows 10 use 2. But the optiplex 990 has placed a heatsink directly behind the pci slot. There seems to connect an independent web site. The dell optiplex 990 also shares the same visual identity as op-tiplex 790 and 390 to offer a more consistent look across the optiplex portfolio and two all-in-one stands enable deployment as a single device with up to 24 displays. PCI SERIAL PORT DELL OPTIPLEX 990 DRIVER (pci_serial_3742.zip)