The best Apple dongle. Is it a Dell DA310?

My attempts to get the perfect video out of an Apple MacBook to the Dell S2721QS finally is a success! It’s all thanks to Dell. I guess it makes sense. Dell makes the monitor, so I suppose having the Dell DA310 USB-C companion adaptor is the right thing to do.

That said, I did expect the Apple adapter to “just work”. I ditched it for the more capable (and gigabit network-enabled!) Dell DA310. The Apple adapter displayed blurry text and icons that really were not sharp. It had to go!

This image shows two Apple adapters sitting on top of each other (left). Both adapters did not correctly work. The Dell DA310, with HDMI and DisplayPort showing, sits on the right next to it.
Two Apple adapters, both adapters that did not work. The Dell DA310 sits next to it.

First, to the Apple USB-C Digital AV Multiport Adapter. You need to be aware that there are two versions of these adapters. Model A1621, which supports 4k video (3840 x 2160) at 30hertz, and the Model A2119, which supports 4k video at 3840 x 2160 at 60hertz. Apple does have a support document, which explains the difference between the two adapters (pictured above, left). Needless to say, I would suggest a different adapter.

One thing to watch out for when purchasing a USB-C adapter is how they mention support for 4k resolutions. Even though an adapter might “support” 4k video, it does not mean that the adapter will deliver a perfect image. Apple mentions that their Model A1621 version of the AV Adapter does not allow screens to operate at a high refresh rate. Even the most recent current model, the A2119 does support high refresh rates – on paper – but not always with a high-quality image.

Why do I care about refresh rates?

High refresh rates make for a very nice operating experience of the computer. Everything from the latency of key presses appearing on the screen, to the smoothness of mouse movements. The limited 30 frames per second of the slower refresh rate afforded by Apple on their older AV Adapters (bottom left adapter, pictured above) is extremely noticeable.

Using a MacBook with a 30-hertz resolution makes the computer feel slow.

Luckily, updating the AV Adapter to the Model A2119 (top left adapter, pictured above) does give 4k video at 60 fps. That said, the quality of the output on the A2119 at a high refresh rate is sad. The colours appear washed out. It almost seems as though the images data is heavily compressed. It’s either done by the MacBook or the USB-C adapter before the data is sent to the display.

Dell S2721QS, shown at 60 hertz with an Apple adapter
Dell S2721QS, shown at 60 hertz with a Dell adapter

It’s hard to be able to visualize the difference between them both side by side. You will notice that lines, such as the diagonal lines on the IntelliJ IDEA icon appear jagged. Switching between the two though, the difference is immeasurable.

Side by Side: Apple A2119 vs Dell DA310
Side by Side: Apple A2119 vs Dell DA310

I’m not sure what exactly is causing this issue. Looking inside System Information, the resolution, refresh rate, connection type settings, and frame buffer depth were all the same.

DELL S2721QS:
   Resolution:        6016 x 3384
   UI Looks like:     3008 x 1692 @ 60.00Hz
   Framebuffer Depth: 30-Bit Colour (ARGB2101010)
   Main Display:      Yes
   Mirror:            Off
   Online:            Yes
   Rotation:          Supported
   Adapter Type:      DVI or HDMI
   Automatically Adjust Brightness: Yes
   Adapter Firmware Version: ff.c1

What’s more, the display artifacts went away on the Apple A2119 when dropping the refresh rate from 60 to 30 hertz. The Dell DA310 experiences none of these issues. Plugging in the monitor using HDMI or DisplayPort gives a crisp, clean image at any resolution with any refresh rate.

DA310 has connectivity galore.

Comparison between the Apple and Dell adapters

Apple USB-C Digital AV Multiport Adapter
Model A2119

  • Connects to Mac using USB-C
  • Provides one HDMI, pixelated 60fps at 4k
  • Provides one USB-A connection
  • Provides one USB-C connection
    (can be used to deliver power to Mac)
  • Provides no network connection
  • Provides no DisplayPort

Dell USB-C Mobile Adapter
DA310

  • Connects to Mac using USB-C
  • Provides one HDMI, smooth 60fps at 4k
  • Provides two USB-A connections
  • Provides one USB-C connection
    (can be used to deliver power to Mac*)
  • Provides one gigabit network connection
  • Provides one DisplayPort 1.4

Although the Dell DA310 does support Power Delivery pass-through (meaning just one cable to the Mac from the Dell adapter), it is documented that the adapter will only allow pass-through for up to 90W. Larger MacBook models come with a 96W charger. However, it is noted that the adapter will chew up some power. This will mean that a MacBook will charge slower.

Some Dell models, like the XPS 15 9500 with NVIDIA GPUs will not receive enough power when plugged into the Dell DA310. Dell recommends connecting the Macbook to the supplied MacBook power adapter directly, skipping the bypass of the Dell DA310.

The USB-C connector only provides 4K @ 30hertz. I am not sure if that kicks in if power pass-through is used, as this was not tested. Only one of the four display outputs can be used at any time.

I have experienced one issue, where the Dell DA310 will occasionally decide that it will not go above 1920×1080. Reconnecting the device resolves the problem.

The gigabit network port is an unexpected bonus, as I got this adapter to fix my 4k issues.

Getting the Gigabit network port to work correctly in macOS will require installing the latest drivers. The chip used for the network is a Realtek RTL8153, the drivers for which are conveniently provided for download from the Realtek website. I was able to download data from my local network at 686Mbps/s. Not bad. Still better than what the MacBook can do when connected to a 2.4Ghz network.

Unfortunately, updating the firmware on the device will require an instance of Windows to run the update software provided by Dell.

Leave a Comment

Your email address will not be published. Required fields are marked *