A HDMI to DVI adaptor is designed to take a video signal from your desktop computer to your HD television, and both video signals will use the same format. The video will transfer without a hitch, but DVI does not have audio options, so you will either need to use a DVI to HDMI converter or a DVI to HDMI adapter with audio. If you are sending the signal in reverse, the video will travel directly from the HDMI to the DVI adaptor, while the audio will need to connect to a sound card or another audio option on your computer. Why would you need a DVI to HDMI adapter cable? For those situations when you don't have an HDMI monitor but still have a device with an HDMI-out function, you can use this type of converter to bridge the gap. The male end of the cable or box plugs into the device's female connector, and the other end plugs directly into the female connector on the display. A DVI to HDMI adaptor is often used when you need to connect something like a laptop to a larger monitor that is not compatible with HDMI.