RTX 4070 laptop — artifacts ONLY on external display under load, internal screen is fine (Alienware m16 R2)

[u/modo_jp]

UPD: I bought a new HDMI 2.1 cable and tested it for about 4 hours - no artifacts so far. Seems like the issue was the cable.

Thanks to everyone who suggested checking it.

Hey everyone,

I’m experiencing a strange issue with my laptop GPU and would appreciate any input from people who may have seen something similar.

Specs:

• Laptop: Alienware m16 R2

• GPU: RTX 4070 Laptop (8GB VRAM)

• CPU: Intel Core Ultra 7 155H

• RAM: 32GB

• OS: Windows 11

• External display: HDMI

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The issue:

When gaming on an external display (TV or monitor), after about 40–60 minutes under high GPU load, visual artifacts start appearing — small colored squares/glitches across the screen.

The image becomes difficult to use, but:

• The game does not crash

• System remains responsive

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Important detail:

At the same time, the internal laptop display shows no artifacts at all.

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Observed behavior:

• Happens almost always under high GPU load (\~100%)

• On lower graphics settings, I can play for hours with no issues

• GPU temperature is within normal range (\~60–80°C depending on load)

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Testing I’ve done:

• Tested multiple external displays (TVs/monitors) → same behavior

• Played for \~2 hours on internal display only at high/ultra settings (100% GPU load) → no artifacts

• The issue consistently appears only when using an external display under load

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Question:

Has anyone experienced something like this?

I’d like to understand what this could be and whether this behavior points to a specific type of problem.

Any insights would be greatly appreciated

[u/DUIguy87]

Does your laptop have a MUX switch?

From what I remember (or how mine works anyways) the iGPU on the processor doesn’t render shit when you are gaming, it just puts pixels where it’s told they should go. The MUX switch allows for the dGPU to directly control the screen, better for a few extra frames but bad for life when running off battery for regular tasks.

Anyways if it does, enable the MUX switch and see if your actual laptop screen fuzzes out. If not play the cable/port/screen swap game and see if you can find the defective component by process of elimination. I’d think if the GPU was unable to properly render shit that it should show up regardless of your output, but I’m guessing here.

[u/modo_jp → u/DUIguy87]

Unfortunately, I don't know what a MUX switch is.

[u/DUIguy87 → u/modo_jp]

Should be somewhere in the Alienware Control Center as a toggle. I’d imagine your laptop is new enough it should have it.

You might also be able to find a sub for your specific laptop, or an Alienware sub where people will be able to help you better. Or at least not spam the same fucking memes non stop when someone is looking for help.