When connecting my Mac to an external monitor via USB C dongle, everything becomes unstable and slow

[fierce spear]

Hello everyone, I came here for support for my M1 MacBook Pro 14 inch.

When I connect my M1 MacBook Pro to an external monitor via USB C dongle the Mac itself becomes unstable for web browsing and video playback, I’ve tried so many different dongles as the problem still pre-sits I’ve also gone to Apple and as usual they told me they don’t know what the problem could be

After checking everything out I can confidently say that my issue is being caused by USB C cables, for whatever reason when ANY Usb C cable is connected to my Mac it just becomes unusable.

[sudden zealot]

Does it happen on all ports?

[fierce spear]

Yes all USB C ports

[sudden zealot]

Have you tried using different resolutions with the monitor to see if that helped?

[fierce spear]

Yeah I’ve tried changing resolutions and refresh rates

[sudden zealot]

macOS is all up-to-date as well?

[fierce spear]

Yeah that’s right, I’m on the latest MacOS Sequoia

[sudden zealot]

What type of connection type is the monitor?

[fierce spear]

HDMI

[sudden zealot]

I'm assuming then it's HDMI to HDMI, which you are then plugging into the USB-C dongle adaptor?

[fierce spear]

Yes that’s right

[sudden zealot]

So a factor that could be causing issues is all gonna come down to what the dongle is rated for. For example, this dongle is rated for 4K 60z:

Do you happened to know what your dongle supports?

[fierce spear]

I’m currently using the Uni USB C dongle https://a.co/d/6Al7IeM

[sudden zealot]

Alrighty, so one thing I did notice is it mention it supports (4K 30z) at highest

Not sure if this is to blame, but it could be

[fierce spear]

Interesting, one of my monitors is the GIGABYTE M27Q https://a.co/d/fx7hygZ

[sudden zealot]

Gotcha, when you connect your monitor to your Mac, do you have the refresh rate set to the max 165hz it mentions?

[fierce spear]

Yeah that’s the thing, I can only go up to 120hz

[sudden zealot]

Well being that the dongle only supports 4K@30, having it at 120hz probably isn't gonna be good.

I don't even think macOS supports 30hz

Try dropping it to 1080p 60 and see if it works

If it does, then the cable is for sure the issue, and you'll need to purchase a cable capabale of 4K@60 or higher if you want

[fierce spear]

Il try that

[fierce spear]

Will do

[fierce spear]

Holy shit, it works!

[sudden zealot]

It did, awesome!

So then it's the cable

[fierce spear]

Definitely!

Thank you so much!

[sudden zealot]

Your welcome!

Can I mark this as resolved or you need anything else?

[fierce spear]

I think I’m set

[sudden zealot]

Alrighty, cool!

[scarlet portal]

Thread marked as 'Resolved/Decided'.

[fierce spear]

Thanks again!

[sudden zealot]

No problem! Glad it's fixed

@fierce spear If you did indeed want 4K 120, this adapter is rated for it: https://www.amazon.com/wegear-Adapter-Converter-Thunderbolt-Compatible/dp/B0DHS51L3L/ref=sr_1_3?

[fierce spear]

Thank you!

🙏

[sudden zealot]

Your welcome!

[fierce spear]

Never mind it’s back,I did a Wi-Fi speed and the results surprised me with the USB C connected and disconnected.

When it’s connected it’s slow

[sudden zealot]

Wow, that is weird. It’s causing interference or something

@misty cargo why might connecting a monitor affect WiFi speeds on a Mac?

[fierce spear]

Interesting

[fierce spear]

Connected via USB C, regular HDMI has no issues.

[sudden zealot]

Huh. Interesting

I never heard of anyone coming across that issue

I use my Mac connected to my monitor via Thunderbolt (USB-C) and I have no issues.

[fierce spear]

That’s very interesting

[sudden zealot]

Then again, that’s Thunderbolt, which can handle a lot more than regular USB-C 3.0

Either way, I’ve used monitors via HDMI in the past and USB-C and it’s been fine too

[fierce spear]

Is it the dongle? I’ve tried others and have been met with the same problem.

The only reason I need to use USB C dongle is for my peripheral s mouse and keyboard wireless usb

[sudden zealot]

That’s the only thing I can think of. If you do try another dongle, make sure it is rated for the specs of your monitor or somewhat close

[sudden zealot]

Gotcha

[sudden zealot]

Such as the one I sent earlier

[fierce spear]

Interesting yeah

Regular HDMI works flawlessly

[sudden zealot]

The HDMI port supports up to 8K output, so it’s fine

[fierce spear]

So I’m not sure why when it comes to USB C

[sudden zealot]

You have the 14 inch MacBook Pro (M1 Pro) right?

[fierce spear]

Yeah that’s the one

[sudden zealot]

So the USB-C is capable then.

[fierce spear]

Should be

[sudden zealot]

Those have Thunderbolt 4 ports

[fierce spear]

Ah interesting, so I need thunderbolt dongle?

[sudden zealot]

You only need Thunderbolt if your monitor is capable, which i don’t think it is.

So you just need a dongle that supports both high resolution (4K as that’s the quality of your monitor), and decent hz, so at least 60, maybe 120 if you can find it.

If that doesn’t work, i don’t know why.

[fierce spear]

Interesting

So it’s a dongle issue?

[sudden zealot]

That’s what I’m thinking

[fierce spear]

Yeah I see what your saying

So the dongle needs to match with my monitor resolution

[sudden zealot]

Yeah, at least if you’re gonna max it out. Which I assume you would cause he paid for a 4K monitor.

[fierce spear]

And I’m assuming your dongle matches up with your monitor

[sudden zealot]

I use one Thunderbolt 4 cable, which was made for the monitor I’m using

[fierce spear]

Ah

[sudden zealot]

But I have used USB-C to HDMI before with no issues running at 4K 60

In the past with a TV

[fierce spear]

Well I need to use USB C dongle for my peripherals

[sudden zealot]

So then the dongle would be the route you’d go with

[fierce spear]

Any recommendations?

So many are the cheap stuff that comes from China haha

[sudden zealot]

Let me take a quick Look through Amazon, give me a bit

https://a.co/d/0M1qBoO

@fierce spear

It’s not 4K @ 120, but it’s at least 60

[fierce spear]

Interesting, was looking for hub for my peripherals

[sudden zealot]

As of hubs, I’m not sure of the best ones, someone else may though

[fierce spear]

Ah right, thank you for the recommendation!

I do have a Ugreen KVM

[sudden zealot]

No problem!

[fierce spear]

Also, forgot to mention that my Mac has black bars in the middle

No physical damage

That’s why I’ve been trying to use external monitors

[sudden zealot]

Oh that’s not good. Did this happen recently?

[fierce spear]

I purchased it like that

[sudden zealot]

I’m assuming it was used?

[fierce spear]

Yeah it was

[sudden zealot]

I wonder if it’s been dropped in its past, but doesn’t have damage

[fierce spear]

Don’t think it has because everything’s working fine.

[sudden zealot]

Hm

[fierce spear]

Yeah, costs around $800 to fix anyways

[fierce spear]

I’m guessing this is a hardware issue

[sudden zealot]

100%

[sudden zealot]

I had a similar issue with my older Mac, but it was covered under warranty

[fierce spear]

Yeah, unfortunately mines already expired

[fierce spear]

For whatever reason the M1 Macs specifically have these hardware issues

[sudden zealot]

Ah

[sudden zealot]

The one I had it happen on was a M2 Pro

That has been the only hardware issue I’ve had with a Mac and I’ve used them for years

[fierce spear]

Interesting

I can probably do the repair myself since I have experience but the panel alone is like $500

[sudden zealot]

Dang