USB C or DisplayPort for best Windows performance?

I have a Surface Laptop 3 with a USB C 3.1 Gen2 (10 Gbit/s) port. Currently, my Surface is connected to the Spectrum via USB C (bandwidth priority set to high refresh rate). However, with the current setup, anything above 4K @ 60hz is limited to 6-bit colour. I can get the depth to 10-bit @ 4K60 by enabling HDR but it appears there isn’t enough bandwidth since the display constantly turns black.

This is the cable I’m using: USB-IF Certified Cable Matters 10 Gbps Gen 2 USB C to USB C Cable 1m with 4K Video and 100W Power Delivery in Black 1 Metre: Amazon.co.uk: Computers & Accessories

The USB C port supports DP 1.4. Could I achieve better performance by using a USB C to DP 1.4 cable?

It looks like the Surface Laptop 3 is limited to 60Hz, both for Intel and AMD CPUs.

https://answers.microsoft.com/en-us/surface/forum/all/surface-laptop-3-displayport-output/0f1208b4-64f8-4cf1-80b9-55bf0635932d

Intel specifications listed their CPUs as topping out at 60Hz, so that doesn’t totally surprise me. I would have thought that the AMD GPUs could do better.

That USB cable looks suspect to me. They say it’s only rated to 10Gbps, but can do 8K @ 60Hz (which needs far more than 10Gbps). If you’re having issues trying to enable HDR, it’s likely that the cable has interference issues and isn’t coping with the higher frequencies needed to carry the data.

Given that you’re limited to 60Hz, you can probably get away with a cable rated at 20Gbps. However, it’s relatively easy to find cables rated for 40Gbps, and they’ll definitely give you the best chance of carrying a stable video signal. I’m using a slightly shorter version of this cable and it’s working great.

2 Likes

Apologies for the very late response - I only just noticed the reply!

It looks like the 60Hz limitation in the thread is referring to the 5120 x 2880 resolution; I can certainly run the Spectrum at 4K 144Hz in Windows - albeit at 6-bit colour depth.

image

I imagine the colour depth is limited to 6-bit due to the bitrate limitations of 4K 144Hz using my 10Gbps cable. The cable can handle this setup or 4K 60Hz (which is what I usually run for the better colours offered by 8-bit) with no issues.

As the USB C port on the Surface Laptop 3 is limited to 10 Gbps (as opposed to 40Gbps for a Thunderbolt 3/4 port) I don’t see how using a 20/40Gbps-certified cable will benefit me (please correct me if I have misunderstood).

What I would like to know, is whether I could achieve better performance (e.g. 4K 144Hz 8-bit) using a USB C to DP 1.4 cable to the Spectrum instead. Perhaps I’ll just have to buy one to test it out.

2 Likes

Thanks for updating us on your findings @Geberna and let us know what kind of refresh rates you can get if you try an USB Type-C to DisplayPort cable!

1 Like