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I have the following hardware:

  • 2021 MacBook Pro (16 Inch) Apple M1 Max - Running macOS Monterey
  • LG Monitor @ 5120x2880
  • Samsung Monitor @ 5120x1440
  • Answin USB C to DisplayPort, 6FT 8K USB-C Thunderbolt 3 to DisplayPort Cable

Connecting each of the monitors to the MBP (two seperate ports) works fine - it drives both 5K monitors without issue.

If I unplug the DisplayPort from the Samsung monitor and connect a Windows PC I can drive it at 5K at 240 Hz. However I don't want to keep un-pluging and replugging the DisplayPort connector to switch computers. Therefore my options are to either find a way to use the HDMI on the Samsung monitor to connect to one of the computers or buy a switch for the Display port connection.

When I try plugging the Mac in via HDMI the resolution drops to 3840×1080, if I try to use the windows PC via HDMI the frame rate drops and the monitor only has 1 DisplayPort connection.

The consensus of the articles I have read is that the MBP can't drive a monitor via HDMI at higher than 4K. Therefore I think I am forced to look for a DisplayPort switch that can handle:

  • The full 5K resolution.
  • The 240 Hz refresh rate.
  • Mac compatible.

Therefore my questions are:

  • What do I need to look for in the switch to ensure the above conditions are met?
  • Does anyone have experience with a particular switch that they know works?
  • Is there any way to get this to work via HDMI or is that a non-option?

Note: It's just the Samsung Monitor I want to switch between the computers - The LG can stay permanently connected to the Mac.

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  • Can you specify which Samsung model you have (including the model number?) This affects the answer significantly.
    – JMY1000
    Sep 28, 2023 at 5:09
  • Samsung Odyssey G9 Neo - LS49AG952NNXZA
    – DavidT
    Sep 28, 2023 at 7:52

1 Answer 1

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I'd recommend a cheap, generic DisplayPort 1.4 switch

As you've discovered, the Samsung Odyssey Neo G9 DQHD (LS49AG952NNXZA) requires a DisplayPort 1.4 connection to operate at 240 Hz—but it strangely only includes one DisplayPort port. It does support 144 Hz at full resolution over HDMI 2.1, but given that this is significantly less than 240 Hz and that the 2021 MacBook Pros only have HDMI 2.0, a DisplayPort switch could actually make sense here.

So, what're our options?

1. A generic DisplayPort 1.4 switch - $20ish

enter image description here

It's a switch! And it should support DisplayPort 1.4. Keep in mind that these switches are very dumb: they're basically just connecting and disconnecting the monitor with a button press instead of a physical cable. EDID emulation (makes the computer think the monitor is still there) is very rare, HDCP (video DRM for stuff like movie streaming) compliance can be hit or miss, and USB passthrough are unlikely to work on any of these. If you're okay with these restrictions though, these tend to do their jobs okay. Even if it doesn't, at worst you're out about $20.

2. A proper KVM - $300-ish

enter image description here

There are tons of cheap KVMs out there. However, in my experience, a lot of them suck—particularly the USB part. If you just need to swap your USB 2.0 mouse and keyboard, there's probably one out there that'll work—but I can't really recommend any of them. There some higher end options, such as the Level1Techs KVM, but they are not cheap: the most basic model sold by Level1Techs is $300. At that point though, you could potentially upgrade to the nicer Samsung Odyssey OLED G95SC DQHD Neo, which supports 240 Hz over HDMI thanks to Display Stream Compression. Unless you really need this monitor or see a KVM as an investment, I'd probably recommend against this option.

3. Switch your HDMI connection around.

Although your MacBook Pro doesn't support HDMI 2.1, if your Windows PC does (or can be upgraded to do so), you can still run at 144 Hz over HDMI at full resolution. This isn't bad by any means, and it could be good either as either a permanent fix or as a stopgap.

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  • Thank you for the response (upvoted) but it doesn't really answer the question / doesn't give me any additional information, the question stated I lose refresh rate via HDMI (#3), I doubt any KVM will handle the full refresh rate (#2), Buying a simply switch is still a crap shoot (#1) - may work, may not.
    – DavidT
    Sep 30, 2023 at 4:16
  • Let me rephrase the content in my answer to make it clearer how it addresses each of those:
    – JMY1000
    Oct 2, 2023 at 4:23
  • #3: Yes, that's a fundamental limitation of your monitor; over HDMI the best you'll get is 5120x1440 @ 144 Hz. However, you noted that "When I try plugging the Mac in via HDMI the resolution drops to 3840×1080"; this is because your MacBook only supports HDMI 2.0, not HDMI 2.1. If you plug your MacBook in over DisplayPort and your Windows computer over HDMI (assuming it has HDMI 2.1 or can be upgraded as such), you'll should get 5120x1440 @ 144 Hz. It's not the full refresh rate, but it's a big improvement over 3840x1440.
    – JMY1000
    Oct 2, 2023 at 4:26
  • #2: The Level1Techs KVM will almost certainly work: it's got extremely good compatibility, supports FreeSync, DSC, HDCP, and EDID emulation. It was recently tested on a similar Samsung 5120x1440 monitor, and it performs well. There was a bug in Samsung's firmware that caused some KVMs to function less well, but this has been rectified as of firmware 1008. It's expensive, but if you want a guaranteed good result, go with it.
    – JMY1000
    Oct 2, 2023 at 4:30
  • #1: Yes, it's a crap shoot. But it's $20 with free returns, versus $300+. In my opinion, it's worth trying. If you want certainty, then go with the Level1Techs KVM. But for $300, you could probably upgrade to a nicer monitor that won't have the issue to begin with.
    – JMY1000
    Oct 2, 2023 at 4:32

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