When you convert video from a source that uses DisplayPort or Mini DisplayPort to DVI or HDMI (for example, a computer to a monitor), you will need to consider the difference between passive and active adapters.
If the source supports dual-mode DisplayPort (also known as DP++), then you can use a passive adapter because the source can perform the conversion. If the source does not support DP++, then you need to use an active converter, which includes additional chips to perform the conversion.
Thunderbolt ports support DP++ natively. To run multiple monitors from the same computer, refer to the Active Adapters section below.
Passive adapters are less expensive since they do not need to include additional chips. A quick way to check whether you can use a passive adapter is to see if the DisplayPort or Mini DisplayPort source has the DP++ symbol above it. The symbol is a D with a P inside of it, with two + signs to the left, one on top of the other.
Active adapters use additional chips to make the conversion inside the adapter, regardless of whether the source supports DP++. This means that active adapters are more expensive than passive adapters.
If you want to use multiple monitors with the same computer, you should use an active adapter because some video cards cannot run the maximum number of monitors while using DP++. This is especially true if the computer has more than one DisplayPort or Mini DisplayPort connection. Check with your video card manufacturer to confirm which type of adapter you need for the setup that you would like to run.