If it is a specific motherboard or laptop/OEM, you can download it from their support site under driver downloads to a USB stick (or download and burn to CD if you don't have one) and then transfer it to the computer that needs the driver.
Also, check that you have installed the latest chipset driver from Intel or AMD (or even EVGA, whichever board chipset you use) and any other drivers for devices that show up in the device manager with a yellow exclamation point, as an unknown device, or just are not there at all.