Kernel Panic With 4k 240 Hz External Monitor

Thunderbolt output is definitely not limited to 60Hz. At 6K the maximum is indeed 60Hz but that is because 6K has much higher bandwidth requirements. These vague specs neither confirm nor deny that higher refresh rates are supported at lower resolutions but in practice macOS does offer up to 240Hz at 4K, so it is actually supported.

Thanks for sharing your experience. This confirms that the issue isn't limited to just M2. M4 Pro seems to behave the same way. The ASUS PG32UCDM monitor has the same Samsung QD-OLED panel as the others mentioned in this thread.

<< I’m really hoping Apple is aware of it ...and will release a fix soon. >>

the thing is, when you post on this User-to-User forum, if other readers can not think of a fix, that's the end of the line. Apple does not troll these forums looking for problems. they need well documented BUG reports that have all the information needed to re-create the problem in their labs. and the more of them they have, the more urgent the problem seems.

<< ... and will release a fix soon. >>

no fix will be forthcoming unless/until YOU and everyone else here reports it as a problem.

you can call Apple telephone support OR

you can use the feedback links and choose BUG REPORT:

Product Feedback - Apple

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No kernel panic on my side since latest firmware update for the moment. Will keep you updated. Do you guys have DSC on or off? I personally have it off as I connect my monitor through DP2.1. Maybe this can have an impact as well... Not sure.

hi, any update here?

I'm getting the same issue and it's pretty critical as the job is lost few times already because us such a HARD restart...

panic(cpu 6 caller 0xfffffe00129b6138): "mismatched swapID's 234895 vs 234897\n" @UnifiedPipeline.cpp:14558
Debugger message: panic
Memory ID: 0x6
OS release type: User
OS version: 24F74
Kernel version: Darwin Kernel Version 24.5.0: Tue Apr 22 19:54:29 PDT 2025; root:xnu-11417.121.6~2/RELEASE_ARM64_T6030

It's already July 18th, and the issue is still present — running at 240Hz still causes a kernel panic! Honestly, it's starting to get really frustrating. I've already sent a million reports — why should I have to put up with this on a $3000 laptop?! Come on, Apple.

Has anyone tried the macOS Tahoe beta? That's my only remaining hope...

According to the status of my bug report, Apple cannot reproduce the issue... which is most likely because they simply don't have a 240Hz OLED monitor. Otherwise, it should be trivial to reproduce. They probably don't consider this issue important enough to buy such a monitor for debugging purposes...

We already provided a reasonable way to reproduce the issue. It’s not our job to try to find an even easier way, and I doubt it would make any difference anyway. Considering the amount of people that could reproduce this issue, I find it very hard to believe that only Apple cannot, *if* they tried with an actual 240Hz monitor. But even if they cannot reproduce the issue for whatever reason, they also have the crash dump. That might be sufficient in itself to debug the issue. But regardless, they didn’t say any specifics on why they couldn’t reproduce the issue, and they didn’t ask for any additional information either. It’s not possible to make any progress if Apple doesn’t want to communicate what is blocking them, so we could help them in a meaningful way. Expecting users to try to guess what they would need is unreasonable. At least, I’m not interested in that.

There’s no other known way to avoid the crash, so everyone should do that, until a fix will be implemented. But this is just a workaround, and kernel panics shouldn’t be left unfixed. Or if Apple doesn’t want to fix this, then they should disable 240Hz support. This is not “just” an annoyance, it might even be a security issue.

I haven't got a panic...yet. I'm using USB-C, and HDR is usually off. However, I did get some artifact characteristic to DSC issues with HDR on after a couple of minutes (the left and right halves of the screen had somewhat different brightnesses) but this could be a bug in the monitor firmware too...

Are you using USB-C or HDMI, and with or without HDR? Thanks!

<< "panicString" : "panic(cpu 2 caller 0xfffffe00440d8440): DCPEXT2 PANIC - apt firmware: dual_pipe.c:180 sync_pipe_end_of_config(). >>

Wow, that sure does look like the same panic all right

Got the Tahoe 26.0.1 update from official/public release channel today, and it only lasted for a few hours before this happened again - right in the middle of a competitive game.

Samsung G93SC (5120x1440 HiDPI @ VRR 48-240Hz), connected via USB-C to DisplayPort.

I mean ... I am using it. It just crashes every 2-3 days once. 🤣

As I wrote in my post.. that is the version I am on. So no …