ROG Stix G731GW doesn't connect to external monitor via USBC-DP

[Nikos_vb]

Hi Everyone,

I have the fallowing issue, can't connect my laptop to my gaming monitor AW2521h using the usbc-DP cable, i had to give up at some point and settle for the hdmi connection. In the past I was able to connect my laptop to a different monitor through the usbc-DP connection,  with some minor issues, had to cycle through the monitor osd imput sources dp>hdmi>dp after each restart.  Also with my current monitor AW2521h I was able in the past to establish a brief connection but it was at random times and very unreliable.  My current monitor is working without a issue being connected to an old PC using directly DP-DP. I also suspected it might be a cable quality issue, so recently I ordered a new cable of the highest quality that I could find but  it didn't seam to matter in the slightest. 

Laptop model is ROG Stix G731GW, Nvidia gtx 2070 gpu

[Anbby_ROG]

I would like to confirm with you whether the laptop's USB-C port can function normally when connected to other devices. 

Additionally, could you provide the version of the display driver you are currently using? This information will help us further investigate the issue. Thank you!

[Nikos_vb]

I have new information since I did the post. Today I went to a friend to test my laptop with his monitor over DP port. And it worked, out of those 2 cables I have only one worked, quite ironically the old cable and not the so called quality cable. Since he had a usbc-usbc cable laying around, I also connected my phone to my laptop with no fuss. Drivers I use are Nvidia latest but I used also the latest from Asus when I was doing the troubleshooting recently, didn't seam to matter.  Now if you are  wondering about my monitor AW2521h DP port, please do check how they washed their hands on the matter (https://www.dell.com/community/en/conversations/alienware-desktops/aw2521h-not-recognized-over-usb-c...). Also I can confirm that recently I re-tested the monitor with my old PC over gtx 570 and its working, connection its most likely DP 1.2, GTX 570 limit

[Anbby_ROG]

As stated by DELL, the DP input port on the AW2521H is designed to be used with its provided the DP-to-DP cable. Using a USB-C to DP cable may result in compatibility issues. Additionally, since the G731GW has been on the market for some time, its DP protocol hardware may not be fully compatible with the latest DP cables. We recommend using an HDMI-to-HDMI connection to connect the AW2521H for the best stability. The above information is provided for your reference. Thank you for your understanding.

[Nikos_vb]

Thank you for your response. However, I would like to clarify a few points about your statement.

1. My G731GW was released in in 2019 and supports DisplayPort 1.4 over USB-C. The AW2521H monitor was released in 2020 and also uses DP 1.4 , so there should be no inherent compatibility issue based purely on release dates. Could you specify what aspect of my laptop’s DP hardware might not be "fully compatible" with standard DP 1.4 cables?

2. While I understand that manufacturers often recommend using DP-to-DP connections, USB-C to DP Alt Mode is an industry-standard feature, and my laptop officially supports it. Additionally, my previous monitor (Acer Predator XN3) worked over USB-C to DP, albeit with minor quirks, suggesting the laptop does properly output DP over USB-C.

3. Both ASUS and Dell mention the importance of 'provided cables,' yet neither ASUS nor Dell (nor most gaming monitor manufacturers) actually supply USB-C to DP cables. If USB-C to DP Alt Mode is not intended to be supported, why do manufacturers advertise DP 1.4 compatibility on their devices without explicitly stating such limitations? Since no official 'provided' cable exists for this connection, how is a consumer supposed to establish a reliable connection within the manufacturer’s recommended guidelines?

4. If there are known firmware or hardware quirks specific to ASUS laptops when using USB-C to DP with certain monitors, could you provide details? Is this a general limitation of the G731GW, or does ASUS have any internal documentation on potential issues with DP Alt Mode compatibility?

I am not looking for a generic recommendation to use HDMI, as that does not meet my requirements. I would appreciate more technical insight into potential limitations of this setup, rather than a general statement on compatibility.

Looking forward to your clarification

[Anbby_ROG]

Thank you for your reply. We understand your concerns and would like to provide a comprehensive explanation.
As you have tested, the G731GW works properly with a C to DP connection when connected to your friend's monitor. However, it is possible that firmware compatibility may cause successful output only with older cables. Additionally, you have also been able to use C to DP output normally with the Acer Predator XN3 monitor.
Since you have only tested the DP to DP cable with the AW2521H monitor for proper output, may we ask if you have tested the C to DP connection with other laptops to confirm whether it displays correctly? This would help us further clarify the issue. Thank you!

[Nikos_vb]

At this point, I have gathered enough evidence to conclude that the issue cannot be resolved without a VBIOS update. This is not a problem related to cables or user-side troubleshooting—it is a firmware-level incompatibility affecting the RTX 2070 Mobile’s ability to output DisplayPort over USB-C to certain high-refresh-rate monitors with a G-Sync module that includes Reflex + Analyzer.

Key Findings:
1.NVIDIA has issued VBIOS updates for desktop GPUs specifically to address DisplayPort-related compatibility issues. Despite this, a Dell community manager attempted to shift responsibility back to the user while knowing that firmware updates have been necessary for full support of DisplayPort, even when using the provided cables. This is evident in the links I will provide.

2.Dell laptops using RTX 2070 Mobile GPUs, such as the Alienware M15 R3, have received BIOS updates as recently as December 2024. In contrast, ASUS’s last BIOS update for this model was in June 2021. If Dell has addressed compatibility improvements through firmware updates, ASUS should provide long-term support as well.

3. How did ASUS resolve USB-C to DisplayPort compatibility with its own PG259QN monitor, which shares a similar G-Sync module with the AW2521H? If this issue was addressed for ASUS’s own hardware, why hasn’t the same been done for third-party monitors?

4.Testing has ruled out all other factors. The issue persists across multiple monitors, with successful output only occurring on models without a dedicated G-Sync module that includes Reflex + Analyzer (e.g., Samsung Odyssey G4, Acer Predator XN3).

The Request:
Since the only real solution is a VBIOS update, I ask ASUS to either:

Acknowledge the issue as a firmware-level incompatibility, or
Provide a timeline for a VBIOS/BIOS update addressing this problem.
I appreciate your time, but I would like to move past generic troubleshooting and focus on a real resolution.

Supporting References:

https://www.nvidia.com/en-us/drivers/nv-uefi-update-x64/
https://www.dell.com/community/en/conversations/alienware-desktops/aw2721d-and-aw2521h-rtx-video-car...

[Anbby_ROG]

Thank you for your feedback regarding the issue with the RTX 2070 Mobile GPU laptop when connecting to a monitor with a Reflex + Analyzer G-Sync module. 

You mentioned that Dell recently provided a BIOS update, which, according to the description, appears to address the Dell Security Advisories (DSA) issue. However, it does not mention any optimization updates related to the issue you described. Could you provide any relevant information for our reference?

To further investigate the issue you mentioned, could you record a video demonstrating the G731GW failing to display when connected to the AW2521H via a C to DP cable, while other devices using the same C to DP cable can display properly on the AW2521H? Please send the video via private message along with the following information, and we will request our technical team to conduct further testing. Thank you.

Required Information:

• Serial Number:
• BIOS Version:
• Windows Build Version: (Settings - System - About)
• dGPU Driver Version:
• C to DP cable brand and model:
• Brand and model of monitors that work correctly using C to DP:

[Nikos_vb]

Thank you for your response. Regarding the Dell BIOS updates, past updates have included unspecified stability and compatibility fixes, and it is known that some manufacturers silently roll in VBIOS updates as well. However, the focus here should be on addressing the clear incompatibility with USB-C to DP on this ASUS model.

As requested, I have recorded a video demonstrating the issue and will provide it along with the requested details via private message.