DVI can (depending on capabilities of the source, display and cable) support VGA (RGB/HV) analog video as well as Digital TMDS Single link or Dual link signals.DVI-I supports both the analog and digital signals. The Digital signals supported can be single or dual link. You cannot tell by looking at the connector of the device whether or not it supports analog video or single or dual link. Why? Many connectors on devices have all of the necessary pins, but they are unconnected inside the device. You should check the devices specifications to see what types of DVI signals are supported. DVI-A supports simply the analog VGA compatible signal exclusively. DVI to VGA connections are always actually DVI-A. DVI-D supports only the digital signals. DVI-D can be single or dual link. mini DVI Switcher FAQ: Nobody usually needs a DVI-I connection. Only one format (digital or analog) can be active at one time.Most DVI Switchers are DVI-D. For DVI-A (VGA) switching, use a DVI to VGA adapter or cable and then just use a VGA switcher - save money!Consider before buying if you need other signals to be switched as well. Also consider if you may need DVI dual link in your future. Monitors over 22" are now often capable of dual DVI links. HDTV's on the other hand are almost exclusively Single link.