Microsoft Surface USB4 Dock Review - Is Intel’s dominance under threat?
Intel’s Dominance
In 2009 Intel (along with Apple) introduced Thunderbolt, a fast and versatile interface for carrying power and all forms of data needed for a docking station. Since then Thunderbolt has maintained dominance over high-end docking stations.
Competing standards did ultimately arrive, however they were unable to match the performance and capabilities of Thunderbolt, until 2019 when Intel opened the Thunderbolt spec and enabled USB-IF (the USB Implementers Forum) to produce USB4 (based on Thunderbolt 3 but with some improvements). Since then newer versions of Thunderbolt are merely certifications for USB4 products.
However even with USB4’s open status Intel maintained a grip on top-end docking station controller chips.
In 2021 Via launched the Via VL830, marking the first non-Intel USB4 controller that could be used in hubs, however that had limited bandwidth capabilities (only a single stream of displayport data at up to 25.92 Gbps and a USB 10 Gbps). Furthermore the Via VL830 lacked downstream USB4 ports (for connecting further USB4 devices), which meant it didn’t meet the official definition for a “USB4-based dock”.
RealTek RTS5490 Controller
The RealTek RTS5490 controller is the first USB4 accessory controller that can saturate a 40 Gbps link. Compared to the JHL8440 controller used in most Thunderbolt 4 docks the RTS5490 offers equivalent display capabilities (up to two streams of 4x HBR2 or equivalent) and higher USB3 capabilities (USB 20 Gbps vs USB 10 Gbps).
The JHL8440 does offer 3 USB4 downstream ports while the RTS5490 only supports 2, however the RTS5490 has a native display output while the JHL8440 requires one of the USB4 downstream ports to be operated in displayport alternate mode. So for docks with DisplayPort/HDMI ports these are equal.
The JHL8440 does offer a PCIe output while the RTS5490 doesn’t, however the JHL8440’s PCIe output was limited to PCIe 3.0 x1 (8 Gbps) so it was mainly used for PCIe ethernet controller chips. Newer docks typically utilize USB3 ethernet controllers (due to improved compatibility and availability) so the RTS5490’s increased USB3 bandwidth compensates for the lack of PCIe outputs.
Surface USB4 Dock Analysis
The Surface USB4 Dock is the first available (and second announced after the Purplelec PEC-TU001-M1) dock to use the RealTek RTS5490 controller chip.
The Surface USB4 Dock features the following ports:
- USB4 upstream (to laptop) port (40 Gbps, 65W power)
- 2x USB4 downstream ports (40 Gbps, 7.5W power)
- 1x USB-A port (10 Gbps, 7.5W power)
- 1x HDMI 2.1 port
- 1x Ethernet (1 Gbps, controlled by RealTek RTL8153 controller)
- 1x USB-C power input
The Surface USB4 Dock does not include an internal MST hub to split a DisplayPort signal, which means that it is limited to 2 displays on USB4 sources or a single display when operating in DP Alt Mode fallback. If desired a DisplayPort MST hub can be connected via the USB4 downstream ports.
Comparison
| Dock | Microsoft Surface USB4 Dock | Microsoft Surface Thunderbolt 4 Dock | Purplelec PEC-TU001-M1 | Purplelec PEC-TU001-01 |
|---|---|---|---|---|
| Price | $199.99 | $299.99 | $56.78 | $88.68 |
| Controller | RealTek RTS5490 | Intel JHL8440 | RealTek RTS5490 | Intel JHL8440 |
| Power | 65W | 96W | 60W | 60W |
| USB4 Downstream Ports | 2 | 3 | 2 | 3 |
| Display outputs (excl. USB4) | 1x HDMI | None | 1x DisplayPort | None |
| Max # Displays | 2 (no MST) | 2 (no MST) | 2 (no MST) | 2 (no MST) |
| Additional Outputs |
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My Testing
I purchased a Microsoft Surface USB4 Dock for testing.
For the most part the dock functioned as expected, however the HDMI port seemed to prevent FreeSync from working and the Ethernet port did not work out of the box on Windows. Connecting my laptop to WiFi while plugged into the dock prompted Windows update to install RealTek software which enabled the Ethernet port to function.
The build quality of the dock feels excellent, however the captive cable and the limited number of ports are disappointing for the price point.
Conclusion
The RealTek RTS5490 is an exciting controller chip due to its disruptive potential to Intel’s dominance, however the Microsoft Surface USB4 Dock has a high price point and limited features making it a tough sell.
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