Kernel Panic With 4k 240 Hz External Monitor

that looks like a 4k display with

• 1x DP 1.4 (HDCP 1.4 & 2.3)(Supports up to 3840 x 2160 240 Hz, DSC, HDR)
• 2 x HDMI 2.1 (HDCP 1.4 & 2.3)(Supports up to 3840 x 2160 240 Hz FRL, HDR, VRR as per specified in HDMI 2.1) (including 1x HDMI 2.1 FRL with eARC - to support Dolby ATMOS signal pass-through)

what interface(s) are you using? how long are your cables?

If you do not have a recent local, disk-based backup, your computer is like a ticking Time bomb. You are only one disk failure, one crazy software, or one "oops" away from losing EVERYTHING! Drives do not last forever. It is not a question of IF it will fail, only WHEN it will fail. In addition, you never know when crazy software or Pilot Error throws away far more than you intended.

If you are using another direct-to-disk backup method that you prefer, and you currently have a recent disk-based backup, that is great. If not, you should consider using Built-in Time Machine. Take steps to acquire an external drive as soon as possible. If you buy one, a drive 2 to 3 times or larger than your boot drive is preferable for long term trouble-free operation. Do not pay extra for a drive that is fast.  (You can get by for a while with a "found" smaller drive if necessary, but it will eventually become annoying).

Attach your external drive and use

System preferences > Time machine ...

... to turn on Time Machine and specify what drive to store your Backups on.  It may ask to initialize the new drive, and that is as expected. APFS format is default format if running MacOS 11 Big Sur or later.

Time machine works quietly and automatically in the background, without interrupting your regular work, and only saves the incremental changes (after the first full backup). Time machine backs up every connected drive that is in a Mac compatible format. it can not back up Windows format drives.

Time Machine's "claim to fame" is that it is the backup that gets done. It does not ruin performance of the rest of the computer while doing its backup operations. You do not have to set aside a "Special Time" when you only do backups. When you need it, your Time machine Backup is much more likely to be there.

How to use Time Machine to Backup or Restore your Mac:

Back up your Mac with Time Machine - Apple Support

I have encountered this issue more than 10 times on my M4 Max MBP.

It happens when using GeForce Now full screen on my 4k 240hz MSI monitor with Mac OS Sequoia 15.2.

I have a case open with Apple with all the panic logs. Will now try 120hz to see if it still crashes.

Just adding another comment for visibility as I'm having this exact same issue.

Was using an M1 Pro MacBook Pro for quite a few months with my 240Hz monitor without any issues, but because of the limitations of the M1 Pro I was limited to 120Hz in the settings.

Recently upgraded to an M4 Pro which supported 240Hz and so updated the settings for the higher speed, and began having intermittent crashes. First thought was of course that it was something to do with the new Mac, but seems this isn't the case.

Seen others on Reddit with the same issue as well, so seems to be a consistent and widespread issue for all users with 240Hz monitors (maybe 4K only??), in fact I have the exact same monitor model OP mentioned.

Would be good to get this resolved.

I also reported it with Feedback Assistant (in late December), same 'Status' and 'Recent Similar Reports' status as yourself.

Can't personally corroborate the Sequoia vs Sonoma story as I've only used my 240Hz panel with Sequoia, but that's a good detail to note.

Definitely needs more reporting this way, as I get the sense 240Hz panels aren't very popular within the Mac ecosystem, given they'll be primarily used for Windows gaming, so this might be overlooked.

Though seems less frequently, I just got another episode on Sequoia 15.4.1.

M2 Max Mac Studio paird with Samsung Odessey G9 OLED (G93SC), Displayport, 240Hz VRR @ HiDPI (7680 x 2160 down to 3840 x 1080).

After recent posts I tried 240Hz on Tahoe, unfortunately it's still not fixed, got a kernel panic

panic(cpu 10 caller 0xfffffe003f2763e0): "mismatched swapID's 782080 vs 782082\n" @UnifiedPipeline.cpp:14910
Debugger message: panic
Memory ID: 0x6
OS release type: User
OS version: 25A354
Kernel version: Darwin Kernel Version 25.0.0: Mon Aug 25 21:17:56 PDT 2025; root:xnu-12377.1.9~3/RELEASE_ARM64_T6030
Fileset Kernelcache UUID: 8860B2D25408AD9DB2C7905AED272C65
Kernel UUID: 6D0E05EA-97D5-3382-AC19-7DB351C560DF

Infilak wrote:

When connected to my Alienware AW3225QF 4k 240 Hz monitor with my M2 Max MacBook Pro, I encounter a kernel panic and a system crash at least once every 2 days. Is this issue specific to the high resolution and refresh rate combo?

panic(cpu 0 caller 0xfffffe001836b410): DCPEXT2 PANIC - apt firmware: dual\_pipe.c:180 sync\_pipe\_end\_of\_config() -- - iomfb\_mailbox(68) apt firmware: dual\_pipe.c:180 sync\_pipe\_end\_of\_config() -- RTKit: RTKit-2758.1.1.release - Client: AppleDCP-811.1.1\~754-t602xdcp.RELEASE !UUID: a1000010-2140-1ed5-a178-80d201401ed5 ASLR slide: 0x000000000021d000 Time: 0x000000090ceeff39

<< I’m not interested in that. >>

Then be sure and set yours back to 120 Hz to avoid the crashing.

I am quite optimistic that this issue can be solved via software update. Just hope they prioritize it somewhat higher. 240Hz displays are not widespread yet and Apple does not sell a display with a refresh rate greater than 60Hz themselves. :(

Reason why .. because for me (M2 Studio) it runs for hours and days without issues doing all kinds of different tasks. Just occasionally (every 2-3 days, after 20+ hours of use) there is one reboot. Does not point usually to a hardware issue ..

I (and several others) have the exact same issue described in this thread using a direct HDMI connection to the monitor. This is obviously a software problem, and in any case it should never cause a kernel panic to select a refresh rate that is provided as an option by Mac OS when connected via Thunderbolt 4.

Same issue here.

MacBook Pro

Mac14,6

Z1760002PCH/A

Apple M2 Max

12（8性能和4能效）

64 GB

Firmware 11881.81.4

11881.81.4

every 2-3 days it's crashed with below error messages.

I also connect to the MSI MPG 322URX QD-OLED which is 4K 240MHZ monitor.

I have upgraded to the latest version of the MAC OS 15.3.1, but the issue is still in there.

panic(cpu 1 caller 0xfffffe0032c512ac): DCPEXT1 PANIC - apt firmware: dual_pipe.c:180 sync_pipe_end_of_config() --  - iomfb_mailbox(70)

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

RTKit: RTKit-2758.80.3.release - Client: AppleDCP-811.80.8~570-t602xdcp.RELEASE

!UUID: a1000010-2140-1ed5-a178-80d201401ed5

ASLR slide: 0x00000000001b7000

Time: 0x000000c7890cb1bd

Unfortunately the kernel panic still happens with macOS 15.4. Also, the status of my bug report in Feedback Assistant has been finally updated after many months to: "Investigation complete - Unable to diagnose with current information"... There is no other update, reply or request for further information (but I'm not sure what else could be provided anyway).

At this point I think it's very likely that Apple will never fix this issue because it seems a kernel panic like this isn't considered important enough. Perhaps the reason is that the panic doesn't happen with an Apple device but with a "third-party" one but it's completely unreasonable to expect that everyone should connect only Apple branded devices to their Macs. These high-end monitors are perfectly stable on PCs with Windows and Linux using various GPUs from different vendors.

yes, BUT:

XDR display

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 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)

Holy...

this issue is so old and i took me days to figure out what is the issue.

I have 2 Samsung Curved Screens (120 & 240 Hz) the 240 Hz crashes frequently my Mac Studio M3 Ultra.

Core Panic Details:

Panic Type: DCPEXT1 PANIC - apt firmware: dual_pipe.c:295 sync_pipe_end_of_config()

Triggering Task: iomfb_mailbox (Task 69) – RUNNABLE at time of panic

RTKit Firmware: RTKit-2784.120.5.0.1.release

AppleDCP FW: AppleDCP-811.120.12.0.1~680-t603xdcp.RELEASE

macOS Version: 14.5 (Build 24F74)

Kernel Version: Darwin Kernel Version 24.5.0

Panicked CPU: Core 18

Relevant Kernel Extensions (Kexts):

- com.apple.driver.RTBuddy

- com.apple.driver.IOSlaveProcessor

- com.apple.driver.AppleDCP

Backtrace Top:

- sync_pipe_end_of_config() (dual_pipe.c:295)

- DCPEXT1 PANIC

- iomfb_mailbox (Task 69)

<< Apple cannot reproduce the issue... >>

if you have a simple setup and a way way to reproduce the crashing every time in short order, contact support and ask them too ADD that setup to the main Bug Report.