ATI DVI to HDMI Adapters

[Seraphic]

I have an ATI 3870 DVI to HDMI Adapter here and I noticed it has all its pins (known as DVI-D (Dual Link).
On the other hand, looked at an ATI 4870x2 DVI to HDMI Adapter and noticed it has missing pins (known as DVI-D (Single Link).
Why would this be since 4870 supports mode audio features then 3870?

http://en.wikipedia.org/wiki/File:DVI_Connector_Types.svg

 

[Seraphic]

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[Digital Viper-X-]

because single link DVI can support 1080p, and all the audio

Unlike HDMI, DVI usually carries no audio data in its TMDS channel. However, as DVI is, for the most part, compatible with HDMI (see Compatibility with DVI), it is just as possible to support including audio data by incorporating the audio in the TMDS signal. Because DVI displays typically have no sound capabilities, a DVI to HDMI adapter/cable can then be used to connect the device to an HDMI display. For instance, this feature allows PCs to send audiovisual data to a high definition television. It is increasingly found on modern computer graphics cards (e.g. cards by Nvidia[1] and ATI[2]) and certain motherboards with integrated graphics.
[edit] Technical discussion