How to connect a 2018 Mac Mini to a Mini DisplayPort Monitor with 4K@60 Hz

[MXBY]

I recently bought the Samsung 27" ViewFinity S90PC 5K monitor (their competitor to the 27" Apple Studio Display).

Besides a Thunderbolt 4 input, this monitor also offers a second input via Mini DisplayPort.
The Thunderbolt 4 input is already occupied by my Mac Studio. I am looking to connect a 2018 Mac Mini via the Mini DisplayPort.

Initially, I tested a USB-C → Mini DisplayPort cable, but to my disappointment this only yielded a 30 Hz framerate at 4K, on the 2018 Mac Mini. I'm not sure why, but I did not have this problem using the same cable with a 2023 M2 MacBook Pro, which supported 60 Hz.


The other options I can imagine right now for the 2018 Mac Mini are:

1. HDMI to Mini DisplayPort.

2. I have a CalDigit TS3 Plus dock that I connect to the Mac Mini over Thunderbolt 3. The dock has a DisplayPort output port. Potentially I can find a cable (or adapter) that takes the dock DisplayPort output *as* Mini DisplayPort input on the monitor.

The first option (HDMI → Mini DisplayPort) probably works, but likely doesn't offer the best image quality.
The second option (DisplayPort → Mini DisplayPort); I'm uncertain whether it works. When browsing, I can't really say for sure if there exists any such cables or adapters. Granted, there exists many Mini DisplayPort → DisplayPort options, but I am looking for the opposite. Not sure if solutions are bi-directional?


What do you recommend me to do?

I am a little bummed that USB-C → Mini DisplayPort cable only offered 4K@30 Hz. Perhaps something to do DisplayPort versions on the 2018 Mac Mini, or perhaps the cable is bad. However, I am confident that full DisplayPort should work with this Mac Mini, as I've been running a 32" monitor over 4K@60 Hz in the past (assuming that the Thunderbolt 3 dock connection supports this with no particular peripherals connected).

 

[joevt]

Mac mini 2018 is limited to HBR2 x4 link rate which can do only up to 4K60 or 5K30.

To get 5K60 from a Mac mini 2018, you need to use a Thunderbolt connection which will output two 2560x2880 60Hz signals to the display but this will only work if the display supports Tiled Mode like the Apple Studio Display or the LG UltraFine 5K.

What USB-C to Mini DisplayPort cable did you use? It should be able to do 4K60 unless it is somehow limited to two lanes of DisplayPort, which would only be true if it was a USB-C dock that support USB 3.x. Make sure the display isn't set to DisplayPort 1.1.

HDMI to Mini DisplayPort cannot be better than USB-C to Mini DisplayPort. It uses a DisplayPort 1.2 to HDMI 2.0 adapter. DisplayPort 1.2 can do 17.28 Gbps but HDMI 2.0 can only do 14.4 Gbps. Maybe if it support chroma sub sampling 4:2:0? It's complicated.

The Mac mini's Intel iGPU has a pixel clock limit which I forget so it might not be able to use the full bandwidth of HBR2 x4.

The CalDigit TS3 Plus DisplayPort output will have the same limits as the Mac mini's Thunderbolt ports.

The DisplayPort signal, whether from DisplayPort or Mini DisplayPort or USB-C is the same signal - there's no difference and no change.

The product page says Thunderbolt 4 is only supported for Apple Silicon Macs? That seems strange. Connect it to the Mac mini 2018 Thunderbolt port and see what it says in the Thunderbolt tab, USB tab, and PCI tab of System Information.app. You can try a direct connection the Mac mini, and an indirect connection through the Thunderbolt port of the CalDigit TS3 Plus. It would be more interesting if you had a Thunderbolt 4 hub such as the CalDigit Element Hub.

Use AllRez to gather info for each connection type (connect the display, run the executable, repeat for each port of the display).
.AllRez > MacMini8,1_Samsung_USB-C_Mini_DisplayPort.txt
.AllRez > MacMini8,1_Samsung_Thunderbolt.txt
.AllRez > MacMini8,1_Samsung_HDMI.txt (but your display doesn't have HDMI so never mind)

You may want to use SwitchResX to get more modes, view the timing info for the supported modes, and add custom modes.

 

[MXBY]

Mac mini 2018 is limited to HBR2 x4 link rate which can do only up to 4K60 or 5K30.

To get 5K60 from a Mac mini 2018, you need to use a Thunderbolt connection which will output two 2560x2880 60Hz signals to the display but this will only work if the display supports Tiled Mode like the Apple Studio Display or the LG UltraFine 5K.

What USB-C to Mini DisplayPort cable did you use? It should be able to do 4K60 unless it is somehow limited to two lanes of DisplayPort, which would only be true if it was a USB-C dock that support USB 3.x. Make sure the display isn't set to DisplayPort 1.1.

HDMI to Mini DisplayPort cannot be better than USB-C to Mini DisplayPort. It uses a DisplayPort 1.2 to HDMI 2.0 adapter. DisplayPort 1.2 can do 17.28 Gbps but HDMI 2.0 can only do 14.4 Gbps. Maybe if it support chroma sub sampling 4:2:0? It's complicated.

The Mac mini's Intel iGPU has a pixel clock limit which I forget so it might not be able to use the full bandwidth of HBR2 x4.

The CalDigit TS3 Plus DisplayPort output will have the same limits as the Mac mini's Thunderbolt ports.

The DisplayPort signal, whether from DisplayPort or Mini DisplayPort or USB-C is the same signal - there's no difference and no change.

The product page says Thunderbolt 4 is only supported for Apple Silicon Macs? That seems strange. Connect it to the Mac mini 2018 Thunderbolt port and see what it says in the Thunderbolt tab, USB tab, and PCI tab of System Information.app. You can try a direct connection the Mac mini, and an indirect connection through the Thunderbolt port of the CalDigit TS3 Plus. It would be more interesting if you had a Thunderbolt 4 hub such as the CalDigit Element Hub.

Use AllRez to gather info for each connection type (connect the display, run the executable, repeat for each port of the display).
.AllRez > MacMini8,1_Samsung_USB-C_Mini_DisplayPort.txt
.AllRez > MacMini8,1_Samsung_Thunderbolt.txt
.AllRez > MacMini8,1_Samsung_HDMI.txt (but your display doesn't have HDMI so never mind)

You may want to use SwitchResX to get more modes, view the timing info for the supported modes, and add custom modes.

Thank you for this answer, very informative!

FYI –

It seems the framerate problem I am experiencing with the USB-C → Mini DisplayPort cable may be related to the display I'm using (Samsung 27" Viewfinity S9, a competitor to the Apple Studio Display, 5K 27"). Potentially this display does not work well Intel Macs. I tried connecting the 2018 Intel Mac Mini with the included Thunderbolt cable (TB4 on both ends) and I get only 30 Hz.

It seems others may have the same issue: https://forums.macrumors.com/thread...al-details-from-samsung.2393056/post-32948954

 

[joevt]

I can't tell what the problem is without some info from AllRez.