MacBook Pro 2016 USB-C to Dual-Link DVI (DVI-DL)

So, you’ve got a nice large 30″ display (e.g. Apple 30″ Cinema Display or Dell 3007WFP) that can render 2560×1600 @ 60 Hz, but it has a Dual-Link DVI connector. And, you have a nice new MacBook Pro 2016 with only USB-C connectors. You might think it would be easy to connect, but this might turn out as a total PITA, because any straightforward solutions (involving simple adapters with physical compatibility) won’t cut it – it’s more complicated…

In theory, it should be possible to drive a Dual-Link DVI display from a USB-C port, and even get the power from the USB-C for the power for the active adapter (that’s the key word: active), but I haven’t yet found one. Moreover, as of now, I know of NO Apple branded product that does the right thing, not even chained together.

The problem is that to “support higher-resolution display devices, the DVI specification contains a provision for dual link. Dual-link DVI doubles the number of TMDS pairs, effectively doubling the video bandwidth” (*wikipedia), but (AFAIK), it does so by encoding a second set of signals on the additional set of pins. That is, it’s not one signal at a higher resolution/refresh, but two that are combined at the monitor to a single image again. That’s what gets you higher resolutions, up to 2560 × 1600 at 60 Hz. Sometimes the connector is called “DVI-DL (dual-link)” but not always, often the name is conflated with simply DVI-D (digital only, an not at all the same thing), and moreover some adapters have the extra dual-link pins, and even claim to be dual-link, but the extra pins aren’t even connected to anything! Finally, dual-Link is not the same as dual-head, though my head starts spinning when I think about this for too long.

Modern HDMI cables can carry resolutions (and refresh) that exceed DVI-DL, but they do it in a single signal path. Adapters from HDMI to Dual-Link DVI simply do not exist, but even if one did, it would need to be an HDMI Type B connector which is not the typical Type A connector you see around.

Display Port is a different beast altogether, and some passive adapters exist, but it too complicates the nomenclature with “Dual-Mode Display Port“, but that’s not the same as Dual-Link DVI, and is not simply electrically (passively) compatible.

In other words, you can’t do go from any physical form factor to Dual-Link DVI with only a passive (physical/electrical wired) adapter. What you need is an active adapter which takes a single-link signal and splits it into two signals on the different sets of Dual-Link DVI pins. Apple does have these for Mini Display Port to Dual-Link DVI, and others exist, but AFAIK, all are Display Port related and all require external power to drive internal chips to split the signal.

So, the solution I have come up with is to use my existing Mini Display Port to Dual-Link DVI adapter from Apple, and then use a USB-C to Display Port adapter. An obvious first choice might be Apple’s USB-C (Thunderbolt 3) to Thunderbolt 2 adapter, but it’s not quite right as it’s *NOT* a Display Port adapter. Don’t try it. Instead, the solution I’m using an Itanda USB C to Mini-DP Adapter.

Note that you still need external power for the mini-DP to DVI-DL adapter, which can be provided by *ANY* USB power port (on your Mac, or powered hub, or even an Apple iPhone or iPad power plug. Depending upon your monitor, you might be able to plug in the USB power to the monitor itself, as I do with my Dell 3007WFP.

Other references that I found helpful:

Other things which might work, some of which have pass-through USB-C power, but I didn’t try: