External Monitor stuck at 30hz?

[imaspeedie]

Hey everyone,

I have a 2016 MBP 15" running 10.14.4 and a new Samsung 28" UR55 monitor. My current setup is my monitor connected via HDMI through my Satechi hub on the left of my Mac.

I understand that my specific Mac doesn't support 4k 60hz out of the box and I'm ok with that atm since I don't need 4k 60hz for work. But my problem is that I'm trying to scale it down to 1080p 60hz but the option to change the refresh rate is greyed out at 30hz?

- It's not the cable because I used the same HDMI cable on my Xbox One X and the monitor registers 4k at 60hz
- My Satechi hub supports up to 4k 30hz (will be switching to Anker's USB-C to HDMI adapter to try 4k at 60hz later)
- I also have the Digital AV hub from Apple that supports 1080p at 60hz or UHD at 30 hz (I plugged in my gf's 2017 Macbook and it put out 1080p at 60hz)

With two different adapters that can for sure support 1080p at 60z and a cable that for sure supports 4k at 60hz. I'm confused why scaling the display stays greyed out at 30hz? Any ideas?

Samsung monitor
Satechi Pro Hub
Digital AV adapter

 

[joevt]

I have a 2016 MBP 15" running 10.14.4 and a new Samsung 28" UR55 monitor. My current setup is my monitor connected via HDMI through my Satechi hub on the left of my Mac.

I understand that my specific Mac doesn't support 4k 60hz out of the box and I'm ok with that atm since I don't need 4k 60hz for work.

You have a MacBook Pro (15-inch, 2016). Of course it supports 4K 60Hz out of the box. It's the Apple adapter and Satechi hub that are limited to 4K 30Hz.

But my problem is that I'm trying to scale it down to 1080p 60hz but the option to change the refresh rate is greyed out at 30hz?

The screen shot shows it is doing 1920x1080 HiDPI mode using the 4K 30Hz timing.

You need to choose the 1920x1080 low resolution mode instead:
- Hold the Option key down and click "Scaled" in the Displays preferences panel.
- Then enable "Show low resolution modes".
- Then select "1920 x 1080 (low resolution)"
- Then select "60 Hertz".

If the "1920 x 1080 (low resolution)" option does not appear, then try installing SwitchResX. I believe SwitchResX will show the proper mode. If not, then create the mode (you'll want to look up the proper values for HDMI 1080p60 mode). Save. Activate Immediately. Select the new timing.
Select "Show best resolutions for display in bold" to make the non scaled timings stand out more. Remember to select the 1920x1080 mode that is not HiDPI and is not scaled.

 

[imaspeedie]

You have a MacBook Pro (15-inch, 2016). Of course it supports 4K 60Hz out of the box. It's the Apple adapter and Satechi hub that are limited to 4K 30Hz.

You're absolutely right. It was def the adapter and hub that were causing the issue. With that being said, I ended up purchasing a USB-C to HDMI adapter from Anker and it worked like a charm. It was only $10 fix so it was def worth it!

I didn't end up downloading SwitchResX, but it could def be another option.

Just a quick note, the Anker adapter will work via my Satechi hub alone, but my current set up has my charger plugged in and both USB-A ports being used so there is def not enough power to go to the monitor and charge my MBP at the same time. Probably would need a self-powered hub to make that work? Haven't looked too much into since I just plugged it into the other side.

Anker adapter

 

[joevt]

With that being said, I ended up purchasing a USB-C to HDMI adapter from Anker and it worked like a charm. It was only $10 fix so it was def worth it!

Why HDMI? The display has a DisplayPort 1.2 connector that has higher bandwidth than HDMI 2.0. The display has support for billions of color (10bpc) but HDMI 2.0 can only do 4K60Hz with 8bpc. 10bpc requires chroma sub sampling (4:2:2 or 4:2:0). DisplayPort 1.2 can do 4K60Hz 10bpc without chroma sub sampling.

Just a quick note, the Anker adapter will work via my Satechi hub alone,

Because the Satechi hub uses two ports from the MacBook Pro, one port for USB-C hub features, and the other for Thunderbolt and PD pass thru. The Anker adapter can work 100% connected to the pass thru port.

but my current set up has my charger plugged in and both USB-A ports being used so there is def not enough power to go to the monitor and charge my MBP at the same time.

Probably would need a self-powered hub to make that work? Haven't looked too much into since I just plugged it into the other side.

I'm not sure what you're saying here. The monitor has its own power source - no power is going to it. Maybe you're talking about the HDMI signal - you can't connect power to the pass thru port and use the HDMI adapter with that port at the same time.

If you really want to connect everything to the same side including power, then you have two options:
a) replace the Satechi with a Thunderbolt dock - it will support 4K60Hz 10bpc with no compromises (up to two displays as well).

b) keep the Satechi. connect a USB-C adapter that supports power delivery and DisplayPort and only USB 2.0, so that there remains four lanes of DisplayPort for max display bandwidth (USB 3.x in a USB-C hub uses two lanes so that only two lanes remain for DisplayPort). Cable Matters has one such adapter:

Cable Matters USB C Multiport Adapter (USB C Hub DisplayPort 1.4), 2X USB 2.0, 480Mbps Ethernet, and 100W Charging in Black - Thunderbolt 4 / USB4 / Thunderbolt 3 Port Compatible with MacBook Pro

Cable Matters USB C Multiport Adapter (USB C Hub DisplayPort 1.4), 2X USB 2.0, 480Mbps Ethernet, and 100W Charging in Black - Thunderbolt 4 / USB4 / Thunderbolt 3 Port Compatible with MacBook Pro

www.amazon.com

but I don't know if 60W is enough.

They have another with 100W:

Cable Matters Dual 4K 60Hz Monitor USB C Hub with DisplayPort 1.4 and 100W Charging - macOS is Not Supported - Thunderbolt 3, Thunderbolt 4, USB4 Compatible for Surface Pro, XPS, Windows Only

Cable Matters Dual 4K 60Hz Monitor USB C Hub with DisplayPort 1.4 and 100W Charging - macOS is Not Supported - Thunderbolt 3, Thunderbolt 4, USB4 Compatible for Surface Pro, XPS, Windows Only

www.amazon.com

It has two DisplayPort outputs using an internal MST hub, but macOS will only let you use one of them. The MST hub may reduce max 4K framerate from 120Hz to 118Hz.