Kernel Panic With 4k 240 Hz External Monitor

I have a ROG PG32UCDM with firmware MCM108 and a Mac mini m4 pro. I connected the monitor with a high quality Thunderbolt 4 usb-c cable so I am certain it is not the cable's problem. This issue still exist on macOS 15.3. As long as I set the monitor refresh rate to 240Hz or 48-240Hz, a kernel panic will occur once a while, especially when mac mini was under heavy load such as running video games. this never happened when I set the monitor refresh rate to 120Hz.

OK, I got some 'good news' here. Been talking to the Apple Support, explaining the situation and just aknowledging.

The person found a 'tracker' about this issue, as of yesterday. Apple team is currently working on this to fix it in an upcoming firmware update. He also said that in the tracker it says that reducing the framerate to 120Hz in the meantime is a workaround in the meantime.

Apple only fixes things that are broken, and broken is often defined as something outside of specifications. For the original Author's Mac:

MacBook Pro (16-inch, 2023) - Technical Specifications - Apple Support

M2 Max

Simultaneously supports full native resolution on the built-in display at 1 billion colors and:

• Up to four external displays: Up to three external displays with 6K resolution at 60Hz over Thunderbolt and one external display with up to 4K resolution at 144Hz over HDMI
• Up to three external displays: Up to two external displays with 6K resolution at 60Hz over Thunderbolt and one external display with up to 8K resolution at 60Hz or one external display with 4K resolution at 240Hz over HDMI

Thunderbolt 4 digital video output

• Support for native DisplayPort output over USB‑C

HDMI digital video output

• Support for one display with up to 8K resolution at 60Hz or 4K resolution at 240Hz

--------

As I read those specs:

higher than 60 Hz refresh rates are ONLY supported on the built-in HDMI port with an ULTRA HDMI 2.1 spec HDMI cable, NO ADAPTERS.

All others appear to be limited to 60 Hz refresh rates, max.

However, kernel panics are NEVER an intended outcome, so 'that it panics' is still a Bug.

The words "dual_pipe" in your panic report suggest that a very strange exceptions condition may be happening here.

there is a display, which runs at somewhat higher resolution and 10-bit color, that should not work because its data rate is too fast for Thunderbolt. But it does work because Apple treats it as two displays on one Thunderbolt connection:

The Apple Pro Display XDR, which macOS allows to connect using two HBR3 connections to a Mac, doesn't support Display Stream Compression (DSC). That [total data rate] would be 51.84 Gbit/s, impossible for Thunderbolt 3, but it works because the two 3008×3384 10bpc 60 Hz 648.91 MHz signals of the XDR display only require 38.9 Gbit/s total and Thunderbolt does not transmit the DisplayPort stuffing symbols used to fill the HBR3 bandwidth.

https://en.wikipedia.org/wiki/Thunderbolt_(interface)

perhaps these troublesome displays have been given the same special treatment, and it is not quite working. I recommend contacting support and asking for a specialist to read your panic reports, as I described above.

I just wanted to share my experience as well. I’m using a Mac Studio (M2 Ultra) with an ASUS PG32UCDP running at 4K 240Hz, and I’m seeing the exact same kernel panic as the original poster. The crash logs show the same “DCPEXT2 PANIC - apt firmware: dual_pipe…” message, and it happens randomly—even with no heavy GPU usage.

I’ve tried both a Thunderbolt 4 (USB-C to USB-C) cable and an HDMI to HDMI cable, but the kernel panic still occurs. So far, the only workaround is to drop down to 120Hz, which isn’t ideal when you have a high-refresh-rate monitor.

Hopefully, this helps confirm that it’s not just an isolated issue. I’m really hoping Apple is aware of it and will release a fix soon. If anyone has further information or a permanent workaround, I’d love to hear it!

—

Mac Studio (M2 Ultra), ASUS PG32UCDP @ 4K 240Hz, macOS 15.3

I also have exactly the same issue (DCPEXT PANIC) with an MSI MPG321 URX (connected via USB-C) and M2 Max MacBook Pro 14". The regular kernel panics happen only with Sequoia (any version). There were zero crashes with Sonoma, so this is clearly a regression. It seems all monitors with 240Hz Samsung QD-OLED panels are affected.

I already reported this issue via Feedback Assistant in November but I still haven't heard anything back. "Resolution" for the report is still "Open" and "Recent Similar Reports: None". Did any of you report the issue this way? Maybe if more users would file reports in Feedback Assistant, the issue would get more attention from Apple.

WilliamIPark wrote:

I'm also getting this issue on a ROG PG32UCDM:

panic(cpu 1 caller 0xfffffe0017b13410): DCPEXT0 PANIC - apt firmware: dual_pipe.c:180 sync_pipe_end_of_config() -- - iomfb_mailbox(50)

apt firmware: dual_pipe.c:180 sync_pipe_end_of_config() --

It seems to occur most frequently when I'm using Discord, which I believe is an app rendering via Electron? I've had some issues with apps like this on Windows too where they behave weird. I wonder is that any clue to the issue?

Anyway, +1 to this needing a fix.

There probably is nothing here for Apple to fix. More than likely you need to use a different higher grade cable.

Later versions of macOS (both major upgrades & minor updates) have changed the communication between devices so that they operate better, but this requires high quality cables. Multiple people in this thread & the multiple other similar threads on this forum have shown that their Kernel Panics & display issues disappeared once they used a high quality cable. The cables which ship with the third party displays from the factory are usually low quality. Plus many cables you find online (or even in physical retail stores) tend to be of low or average quality.

Users here are seeing this as something Apple accidentally broke, when in fact it is really Apple trying to make things work better for the newer higher resolution HD displays which require the communication between devices to be much more reliable than with older lower end devices since there is much more data needing to be transferred for a clear flicker free picture. These changes just happen to require people to purchase a higher quality cable. See any one of the hundreds of posts on this forum by @Grant Bennet-Alder regarding display related issues for more information & a much better explanation than I have given here. @Grant is the forum resident expert on all things related to macOS/Apple displays. Take what he has to say very seriously...he knows his stuff.

It would really be nice if Apple actually mentioned & explained such changes to users so people are not blindsided by them, but Apple is very poor at communication.

You can always provide Apple with product feedback here since Apple does not participate on this forum & it is doubtful any engineers are reading these posts:

Feedback - macOS - Apple

And you should also provide feedback to the display manufacturer as well since ultimately it is the third party manufacturer that needs to make sure their product works with other devices (assuming they claim to support such a device).

We are enterprise customers in Europe. I talked to the EU team ans they can’t forward this to US.

if some one is enterprise customer in US please talk to ur business manager and ask him to forward this.

this bug still exist in the beta.

we can reproduce this issue on MacStudio and MacBook Pro.

current fix is : set display to 120Hz.

based on your having:

"M2 Max MacBook Pro"

... it should be massively LOAFING running that display with either of those setups.

Your panic appears to be some sort of Display Co-Processor (DCP) Panic, but I don't see much there to gloom onto.

How about an Etrecheck report?

Consider downloading and running this little "discovery" utility, Etrecheck. It changes NOTHING. Etrecheck was developed by senior contributor here, and uses system calls to collect often-needed information.

it contains little tests for speeds of devices, CPU utilization, memory usage, energy usage and a digest of recent problems, in one easy to use package. it does not even need to be Installed. Because less can be learned when your Mac is running great, best time to run is when your problems are actually occurring, if possible.

if you follow the directions faithfully, its report (pre-laundered of all personally-identifiable information) can be "Shared" to the System ClipBoard, then Pasted into an ‘Additional Text’ window in a reply on the forums.

Use Etrecheck Pro for free:

http://Etrecheck.com

then start a reply on the forums and use the additional text icon in the reply window footer, and PASTE the report

...

Having the same issue on a Mac Studio (M2 Max) connected to a Samsung G93SC DQHD running at 48-240Hz VRR, 5120x1440, which is less demanding than 4K 240Hz. Frequent (daily?) crash and reboot on Thunderbolt - DisplayPort.

I'll downgrade to 120Hz for the moment and watch this thread. At least I know that this is a MacOS bug rather than faulty monitor or Mac.

Have not seen a single crash since setting it to 120hz

I fixed this... They updated my firmware at the Apple Store... I have a MacBook M2 Pro and a 240hz monitor....

swalexander1 wrote:

I fixed this... They updated my firmware at the Apple Store... I have a MacBook M2 Pro and a 240hz monitor....

what exactly did they update?

Error msg was exactly the same. But for me it stopped when I switched from adaptive refresh rate to locked 120Hz.