OWC Thunderbolt Dock: mini-review, mixed impressions

[cfm56d7b]

I ordered OWC Thunderbolt Dock https://eshop.macsales.com/shop/owc-thunderbolt-dock as soon as the device became available.

After 8 weeks of extensive testing with the latest 2020 MacBook Pro 13" 2.3 GHz Intel based laptop, the dock hasn't performed as expected.

Mini-review:

1. Ethernet port stops working intermittently which required the dock to be power cycled. There is a growing body of evidence the problem is rooted in Realtek RTL8153 chipset also used in many other hubs and docks. Realtek hasn't yet provided a Big Sur DriverKit compatible driver so Big Sur utilizes Apple provided default driver. Hubs and docks which use Intel-based Ethernet chipset do not exhibit the same problem.

2. After waking up from sleep, previous video resolutions are not honored on 2 x 4K Dell monitors and both monitors reset to a lower resolution. With the dock removed and both monitors attached directly to the laptop, waking up from sleep works as expected. All resolutions are preserved.

I worked extensively with OWC technical support and at the end shipped the dock back to OWC.

 

[joevt]

1. I prefer PCIe Ethernet controllers (the Intel ones you mentioned) over the USB Ethernet controllers (the Realtek ones). I've actually never tried a USB controller.
One option is the connect the Apple Thunderbolt to Gigabit Ethernet controller to an Apple Thunderbolt 3 to Thunderbolt 2 adapter since the Thunderbolt 4 Dock has 3 downstream Thunderbolt ports to use. But if the other 2 ports are used for displays, then you're out of Thunderbolt ports. In that case, you could add a Thunderbolt to Dual DisplayPort adapter to save a port.

2. That's a strange one. I can't think of why this would fail. Are they DisplayPort 1.2 displays (4K60 10bpc max)? Are you able to change the displays back to the higher resolution without disconnecting or reconnecting anything?

 

[cfm56d7b]

1. I prefer PCIe Ethernet controllers (the Intel ones you mentioned) over the USB Ethernet controllers (the Realtek ones). I've actually never tried a USB controller.
One option is the connect the Apple Thunderbolt to Gigabit Ethernet controller to an Apple Thunderbolt 3 to Thunderbolt 2 adapter since the Thunderbolt 4 Dock has 3 downstream Thunderbolt ports to use. But if the other 2 ports are used for displays, then you're out of Thunderbolt ports. In that case, you could add a Thunderbolt to Dual DisplayPort adapter to save a port.

2. That's a strange one. I can't think of why this would fail. Are they DisplayPort 1.2 displays (4K60 10bpc max)? Are you able to change the displays back to the higher resolution without disconnecting or reconnecting anything?

Both displays are Dell U2720QM connected via Dell-supplied TB (USB C) cables. The resolution can be changed without disconnecting. When both monitors are connected via OWC dock, the resolutions are reset after waking up. OWC has not provided any meaningful guidance.

 

[joevt]

2.3 GHz means you have MacBook Pro (13-inch, 2020, Four Thunderbolt 3 ports) with quad‑core 10th‑generation Intel Core i7. This is an Ice Lake CPU that supports up to DisplayPort 1.4 (HBR3)

The Dell U2720QM has two (or three) USB-C modes:
1) High Resolution: USB 2.0 with 4K60 10bpc using 4 lanes of HBR2
2) High Data Speed: USB 3.0 with 4K30 10bpc (2 lanes HBR2) or 4K60 8bpc (2 lanes HBR3).

Which mode are you using? Have you tried the other mode?

The Dell OSD menu can show the Display Info Link Rate (HBR2 or HBR3). What does it show?

You can get the link rate in macOS using the following command:
/System/Library/Extensions/AppleGraphicsControl.kext/Contents/MacOS/AGDCDiagnose -a > AGDCDiagnose_a.txt 2>&1
Maybe grab some examples for all the situations. Two displays before sleep, after sleep, after restoring proper resolution. Repeat for each USB-C mode. Rename the output file for each test with a number and a description.

I wonder if macOS allows two DisplayPort connections of two lanes of HBR3? Thunderbolt can support it but maybe this mode is not automatic after sleep.

Thunderbolt can't support two connections of 4 lanes of HBR3. The macOS driver or the Thunderbolt dock may be confused when seeing two HBR3 displays but it shouldn't be a problem if they only request 2 lanes.

Maybe using USB 2.0 mode will give less trouble but not if the display reports having 4 lanes of HBR3.

Do you experience the resolution problem if only one display is connected to the dock?

 

[cfm56d7b]

When both Dell U2720QM monitors are connected directly to the laptop (1 left TB port, 1 right TB port), everything works. The video resolutions - and all open windows - are rendered correctly when the laptop wakes up from sleep. So Big Sur 11.6.1, Apple's video drivers, Dell hardware - and all components between - work as designed.

The output from the command you suggested is below (with both monitors attached directly to the laptop).

The OWC Thunderbolt dock - when introduced between the laptop and 2 x Dell U2720QM monitors - fails to act as a passthrough device for reasons unknown. And that's the problem. OWC cannot explain it. Plus Ethernet port fails intermittently. The problem with RTL8153 chipset and absence of DriverKit compatible driver has been documented by many others.

How both Dell monitors appear in System Report connected directly to the laptop:


DELL U2720QM:


Resolution: 6016 x 3384


UI Looks like: 3008 x 1692 @ 60.00Hz


Framebuffer Depth: 30-Bit Color (ARGB2101010)


Display Serial Number: _______


Main Display: Yes


Mirror: Off


Online: Yes


Rotation: Supported


Automatically Adjust Brightness: Yes


Connection Type: Thunderbolt/DisplayPort


DELL U2720QM:


Resolution: 6016 x 3384


UI Looks like: 3008 x 1692 @ 60.00Hz


Framebuffer Depth: 30-Bit Color (ARGB2101010)


Display Serial Number: _______


Mirror: Off


Online: Yes


Rotation: Supported


Automatically Adjust Brightness: Yes


Connection Type: Thunderbolt/DisplayPort


Output:

Dumping EFI data for GPU Path IOService:/AppleACPIPlatformExpert/PCI0@0/AppleACPIPCI/IGPU@2
GraphicsDisplaySetup:
Version 65536
ConnectorNumber 0
AvailableLanes 4
AvailableBitRate 3240
DisplayRestoredFromNVRAM 0
HibernateWake 0

DP Configuration
Version: 65537
Mode: 0
BitRate: 4294901760
Lanes: 4
CommonVoltage: 0
CommonPreEmphasis: 0
CommonPostCursor2: 0
EnhancedFraming: 1
Scrambling: 1
AlternateScramblerSeedReset: 0
OtherBitRateInMegaBitsPerSecond: 3240

Framebuffer Timing
TimingIndex: 0
Encoding: 1
BitDepth: 3
PixelClock: 260730000
HActive: 2560
VActive: 1600
HBlank: 80
HBorderLeft: 0
HBorderRight: 0
VBlank: 46
VBorderTop: 0
VBorderBottom: 0
HSyncStart: 8
HSyncWidth: 32
HSyncPositive: 1
VSyncStart: 32
VSyncWidth: 8
VSyncPositive: 0
Interlace: 0

Framebuffer resolution
Version: 65536
Width: 2880
Height: 1800
Stride: 0
Format: 1
Rotation: 0
Reverse: 0

 

[joevt]

When both Dell U2720QM monitors are connected directly to the laptop (1 left TB port, 1 right TB port), everything works. The video resolutions - and all open windows - are rendered correctly when the laptop wakes up from sleep. So Big Sur 11.6.1, Apple's video drivers, Dell hardware - and all components between - work as designed.

The output from the command you suggested is below (with both monitors attached directly to the laptop).

The OWC Thunderbolt dock - when introduced between the laptop and 2 x Dell U2720QM monitors - fails to act as a passthrough device for reasons unknown. And that's the problem. OWC cannot explain it. Plus Ethernet port fails intermittently. The problem with RTL8153 chipset and absence of DriverKit compatible driver has been documented by many others.

How both Dell monitors appear in System Report connected directly to the laptop:

Output:

Dumping EFI data for GPU Path IOService:/AppleACPIPlatformExpert/PCI0@0/AppleACPIPCI/IGPU@2
GraphicsDisplaySetup:
Version 65536
ConnectorNumber 0
AvailableLanes 4
AvailableBitRate 3240
DisplayRestoredFromNVRAM 0
HibernateWake 0

DP Configuration
Version: 65537
Mode: 0
BitRate: 4294901760
Lanes: 4
CommonVoltage: 0
CommonPreEmphasis: 0
CommonPostCursor2: 0
EnhancedFraming: 1
Scrambling: 1
AlternateScramblerSeedReset: 0
OtherBitRateInMegaBitsPerSecond: 3240

Framebuffer Timing
TimingIndex: 0
Encoding: 1
BitDepth: 3
PixelClock: 260730000
HActive: 2560
VActive: 1600
HBlank: 80
HBorderLeft: 0
HBorderRight: 0
VBlank: 46
VBorderTop: 0
VBorderBottom: 0
HSyncStart: 8
HSyncWidth: 32
HSyncPositive: 1
VSyncStart: 32
VSyncWidth: 8
VSyncPositive: 0
Interlace: 0

Framebuffer resolution
Version: 65536
Width: 2880
Height: 1800
Stride: 0
Format: 1
Rotation: 0
Reverse: 0

The output from System Report is next to useless which is why I didn't ask for it.

The AGDCDiagnose output is missing the important parts. Zip the result .txt file and attach the entire thing to your post. The part you did include does mention "AvailableBitRate 3240" which I guess is HBR3 (8.1Gbps) x4 but this is during the boot EFI environment which we don't care about at the moment.

You didn't answer any of my questions or perform any of the tests I suggested.