The new MacBook Pro with the M1 chip is a giant leap in performance, energy efficiency, and value for money. So I upgraded from my 15-inch MBP 6-core i7 (2018) to a 13-inch M1 MBP (2020). However, my euphoria for the M1 MBP confined when I found out about the restriction of only one external display.
I read about the workarounds using DisplayLink’s Video-Over-USB dongles. At first, I shrank back from that idea, having used earlier DisplayLink dongles several years ago with severe performance issues. However, now with USB3 and Apple’s new M1-chip architecture, I gave DisplayLink another chance.
There are several different DisplayLink dongles available from various manufacturers with significant differences in prices. Important to know is that all those manufacturers put the same DisplayLink chips in other plastic boxes. The only factor that matters is which DisplayLink chip is built into the dongle. For deciding on the chipset, DisplayLink provides a comprehensive overview on their website. I decided for the DL-6950, which is currently the top-end chip in terms of highest resolution, refresh rate, and performance. As dongle, I chose the one by i-tec, as this was the best in terms of price and availability. However, technically identical is, e.g., also the one by StarTech.
The performance of the 4k via DisplayLink on the MBP M1 is absolutely stunning. I ran multiple benchmark tests, comparing the M1’s performance with my previous 15-inch MBP i7 2018 performance (with native Radeon Pro 555X GPU). As a benchmarking tool, GFXBench 5.0 Metal turned out to be the most suitable for my regards. It plays through different graphic intense 3D-games and thereby measures performance. The value of interest here is FPS (Frames Per Second). All values above 25 FPS are acceptable, as 25 FPS is the threshold for moving images to appear fluid.
The benchmarks show that a 4k display via DisplayLink on the M1 mac outperforms a natively connected display on the 2018 MBP with native GPU. In fact, the M1-Displaylink FPS performance is more than 5-times higher than Radeon-Native performance. During the benchmarks, the MBP M1 fans did not even start, while the 2018 MBP was making sounds like an airplane at takeoff. This is mind-blowing.
Unfortunately, there are some limitations of the DisplayLink connected Displays. First of all, it does not support HDCP. Therefore, if DisplayLink is active, there is no playback of protected content, like for Netflix or most other streaming platforms. For me, not really a problem at all. What actually really frustrates me is that there is no support of HiDPI /Retina resolutions above 1080p. The only resolutions to choose are HiDPI 1080p (too large) or native 4k resolution (too small). Usually, with software like RDM (v2.5 or above for M1 support) or SwitchResX one can overwrite the resolutions offered by the display or Mac OS (since Catalina officially supported with overwrite files in /Library/Displays/Contents/Resources/Overrides). However, DisplayLink ignores these overwrites. So, at the moment, we need to wait for DisplayLink (or Apple) to improve this drawback. Another issue many users report is the missing clamshell mode (using the MBP with lid closed and external screen, keyboard, and mouse). I bypass this issue, as I am having one natively connected external display besides the DisplayLink external display. So, clamshell mode works fine for me. Lastly, there is also limited support for color calibration profiles, and therefore NightShift or F.Lux does not work on Display Link.
Summing it up, I use a 4k display over DisplayLink on a daily basis for two months now. Besides the HiDPI issue, I am highly satisfied and experiencing no other issues. Everything runs smooth, fluid, and as perfect as if the display was connected natively. Plus: I get the overall performance and battery boost of the M1 MBP.
I sold my 2018 MBP on ReBuy, receiving roughly the same amount as the new M1 MPB costs. A great deal.