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UHD Graphics with no 120Hz support for Ultrawide 5120x1440

Udzi
Beginner
1,175 Views

Hi everyone,

as the title already says i own a ultrawide monitor with a resolution of 5120x1440 and 120Hz refresh rate from Samsung (C49RG94SSU). The latest drivers for my UHD Graphics are installed (30.0.100.9864) and i use a high-speed USB-C to DisplayPort cable. Unfortunately, the maximum possible refresh rate to choose is 60Hz although the cable, port, graphics and monitor should support it. I tried another cable, with my dockingstation (WD19TB) with no luck.

On another PC, 120Hz works fine. I can't imagine that 60Hz is the limit, there must be a problem with the driver. Especally because the Intel Driver & Support Assistant reports that 120Hz is possible (screenshot attached).

I need help 🙂 Thanks in advance

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1 Solution
n_scott_pearson
Super User Retired Employee
1,082 Views

If you have UHD graphics, then yes, you are limited to DisplayPort 1.2. You are correct if the connection is true TBT, however - but it will still be limited to 60Hz.

...S

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n_scott_pearson
Super User Retired Employee
1,135 Views

Intel UHD Graphics supports DisplayPort 1.2. Per this article: https://en.wikipedia.org/wiki/DisplayPort, DisplayPort 1.2 supports a maximum data rate of 17.28Gb/s. Supporting a 5120x1440 resolution at 120Hz requires a data rate of 23.18Gb/s, so 120Hz is simply not possible. With a really, really good cable, you might be able to get away with 85Hz (data rate of 16.14Gb/s), but I am betting that 60Hz is the best that you are going to do.

Now, if a docking station is in the picture, the situation becomes even worse. In this case, only two of the four USB-C transmission channels are going to be available for the DisplayPort connection and this means that 30Hz becomes the best you will be able to do. This is because one or two transmission channels will be consumed by the USB connectivity (also) demanded by the docking station.

Sorry, reality bites. This 'other PC' must have a newer (non-UHD) processor with DisplayPort 1.4 support.

...S

Udzi
Beginner
1,095 Views

First of all, thank you for your fast and good answer Scott. This is a new information, i thought DP 1.4 was the used protocol and capable from such a new device (Dell Precission 5550). Are you really sure about the limitation of DP 1.2? If so, why does Support Assistant show 120Hz as maximun with the display?

A supplementary sentence about the docking station: It's a WD19TB, so it's Thunderbolt, 60Hz works fine here via a normal DisplayPort Cable.

You are right, the other PC has a GTX1050 installed...I just wanted to express that the monitor can definitely do 120Hz

n_scott_pearson
Super User Retired Employee
1,083 Views

If you have UHD graphics, then yes, you are limited to DisplayPort 1.2. You are correct if the connection is true TBT, however - but it will still be limited to 60Hz.

...S

Udzi
Beginner
1,064 Views

Ok thank you. One last question regarding data rates and docking stations: Do you think a TB18DC will be a possibility? This Docking has a connector for two USB-C Ports.

 

EDIT: Nevermind, ive just read that its only compatible with 7530/7730 Workstations

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