Compatibility Test: Helios FX, Mac Mini and macOS 10.15 Catalina

OWC Mercury Helios FX 650

Prior to the release of any new macOS, we make a concerted effort to test as many of our products as we can with the new OS, using a variety of hosts and configurations. The Helios FX series of products is no exception. Test results showed no significant changes in behavior or performance from previous compatible OS versions.

However, in the days since macOS Catalina was released, various online publications and individuals have noted problems when using specific GPUs in combination with Catalina and the 2018 Mac mini series.

We decided to investigate this ourselves, and the results have been mixed thus far. While we cannot definitively say that a 2018 Mac mini running Catalina will not work with the Helios FX or other eGPUs, there are clearly some scenarios which are producing more issues than others.

2018 Mac mini

Specifically, we are considering a change to our compatibility listings with respect to Radeon RX x00 series cards, such as the RX 480 and RX 580 series, as well as a limited number of specialized cards like the Radeon Pro WX 7100. Thus far, we have encountered no critical issues with higher-end cards like the Vega 56 and 64 series, and only limited issues or pre-existing issues with the Radeon VII and Radeon Pro WX 8200. Again this is all specific to the 2018 Mac mini series; we do not have any reason at this time to think it impacts other series like the MacBook Pro.

Tests are ongoing, but at this time, if you are running a 2018 Mac mini with an eGPU like the Helios FX, on 10.13.4 High Sierra – 10.14.6 Mojave, and you are not experiencing any issues, it may be a good idea to delay your upgrade to macOS 10.15 Catalina for the time being.




  • I attempted to post a comment earlier, but it hasn’t appeared, so let’s try again…

    I applied the latest 10.15.4 update a few days ago and have had blissful fan silence from my Helios FX 650 since rebooting. So, I decided to post about my success.

    Of course, half an hour AFTER posting that message the fan started up again! I did a reboot and it went away again. It’s chirped up a few times but then ramps back down to silence. It’s so random.

  • Since the Catalina 10.15.4 update everything seems to be working fine now. No more switching the cable back and forth between the Mac Mini and the eGpu anymore.

    The boot screen is black but it boots fine now..
    Helios FX, RX580, 2018 Mac Mini.

    • Yes. My Helios FX 650 fan has finally settled down.

      I’ve been running 10.15.4 for 5 days now, so (reasonably) confident the latest MacOS patch has finally fixed this annoying problem.

  • The Helios FX 650 and Sapphire RX 580 boot fine with a Display Emulator plugged into the mini’s HDMI port so I at least get screens on boot.
    When I start the mini, I get neither boot nor login screens – just both displays with the Catalina image on them.
    I ‘blindly’ hit the correct keyboard letter to select the required user account and type my password. In a few seconds the screens flash and I get normal desktops and menu bars. Not optimal, but at least I don’t have to pull cables!

    My biggest issue is the FX 650 fan going nuts! There is no rhyme or reason to when it decides to go to full power. I’ve had a full day with no fans noise – merely an occasional flutter of the RX 580’s card’s fans. Some days the FX 650 fan will go wild after a few minutes, or a few hours. It sometimes ramps up and down a bit – probably 70% and then back up to 100%. I end up putting the mini to sleep in the hope it will ‘reset’ for a while. Sometimes it does…

    It is annoying as other than the fan screaming at me the FX 650 works a treat with the 2018 Mac mini. Some people are saying the latest Catalina beta is giving them boot screens, so I can only hope it also fixes this issue.

    Anyone else with this same fan problem with the FX 650 and Sapphire RX 580 combination?

    • Hey Mark,

      I would reach out to Customer Service and let them know what’s going on. They may be able to shed some light on things if they have heard of other users having problems. If not, it will be good for them to know so they can keep an eye on things.

      • Thanks for the suggestion, however the OWC Support Team are already aware and responded to my original queries:
        “The erratic fan speeds are a symptom we’ve seen on the macMini8,1, one of the reasons why we do not recommend the two together. If you have another Thunderbolt 3 machine running Mojave, you could connect it there and observe the fan speeds – I’m relatively sure you’d see them run as intended there.”

        I’m waiting for the Catalina update and will then pursue this further – there is still a possibility I have a faulty unit. However, downgrading to Mojave is not an option for me.

  • I seem to have luck by one of two means. One… On the 2018 Mac mini, attach a second monitor to the built in HDMI port. Once you have the log in screen, you can disconnect the second monitor.

    This one works “sometimes”… Just boot up, when the screen turns white, green or black, turn off the EGPU for 5 seconds, then turn it back on. This sometimes gets you to the log in screen.

  • I have a 2018 MacMini using the Helios FX bundle with the AMD Radon RX 580 card, and indeed there are significant issues as you are discovering. I can get the system to boot by disconnecting the eGPU till after it is fully booted, then “add” the eGPU and the system does recognize it and then adds the 2 additional monitors plugged into the eGPU. I have to use a third monitor direct from the docking station to support the boot process. I am running the latest Catalina 10.15.1.

    If I restart the system with the eGPU connected normally, about half way through the boot process, when it is trying to connect the eGPU, my direct monitor gets hung, the eGPU fans shift to high gear, and I get purple lines on one of the two eGPU monitors. If I then unplug the eGPU, the boot process completes with the one direct monitor, then after booting, plugging in the eGPU seems to work as described above.

    I am signing up for updates!

  • I am having issues with a 2018 Mac Mini and Helios FX and Radeon RX 580 after installing macOS Security Update 2019-001 (Mojave) tonight. My screen was showing the progress bar on reboot, but eventually hung and showed signs of graphics anomalies including several bright flashes and purple lines on the boot screen. I never made it to the macOS login window until I powered off the Helios FX and switched my monitor back to the HDMI output of my Mac Mini.

  • I am having issues with a 2018 Mac mini and Helios FX 650 with Radeon RX 580 installed. Mojave 10.14.6

    Two Dell P2715Q’s connected via DisplayPort to the RX 580, one display runs at 3840×2160 60Hz, the second display will only run at 1920×1080 60Hz for some reason, not sure why. Pressing option when selecting “scaled” doesn’t show any options above 1080p. What could be the issue?

    • Hi,

      There are no known issues with the Helios FX and/or the Radeon RX 580 on 10.14.x at this time. The scenario you’re describing sounds like you may have hit the total resolution limit of the GPU. This type of scenario can be seen not only with eGPU setups but (for example) when connecting multiple displays to a laptop via a hub or dock. In some cases you may be able to resolve the situation by disconnecting the display that is showing the lower resolution and reconnecting it, or ejecting the eGPU (from the menubar), disconnecting the Thunderbolt 3 cable and then reconnecting it to the host. While it doesn’t always make a difference I have seen this work when one or both connected displays are showing a lower than expected resolution.

    • Hi,

      I looked into this for you a bit more and I can confirm that dual 4K is possible, at a minimum, using this configuration:

      2018 Mac mini running 10.14.6
      Helios FX 650
      Gigabyte RX 580 (the brand shouldn’t matter much, it’s the reference design from AMD that matters)
      Dell 4K via DP @ 60Hz
      HP 4K via HDMI @ 30Hz

      The display models are not the same as the ones you’re using but in principle dual 4K is possible. It may be worth your while, if the earlier suggestion did not help, and you have a spare cable available, to try and connect one of the displays via HDMI.

      • I was able to solve the problem, turns out one of my DisplayPort cables was failing. All is well now with 2018 Mac mini and Radeon 580 in the FX 650, although I still get the white screen whenever I restart. I solve this by temp connecting an HDMI display to the Mac mini directly, then removing the HDMI cable once the mini is done booting. I’m still on Mojave waiting for Catalina compatibility. Did 10.15.1 fix anything?

  • I’m hoping we’ll be seeing tests soon for the Aura SSD and other related products!