Permanently attached HDMI on a mini without activating the iGPU?
 
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Permanently attached HDMI on a mini without activating the iGPU?  

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Leovinus
(@leovinus)
Estimable Member
Joined: 1 year ago
 

My Mac mini (so far) works flawlessly booting with the eGPU in both bootcamp and MacOS. No HDMI attachment to the mini required.

Thing is, I don't need the eGPU for 80% of my day. So I generally plug in the HDMI and disable the eGPU to save on noise and power draw. As having the HDMI connected when I DO want to use it saps performance something fierce (and is also less stable) I unplug the HDMI from the mini every time I want to use the eGPU. Several times a week. It's a hassle and probably not great for the longevity of the port.

I was thinking, would buying a sacrificial extension cable from where I can attach or remove the HDMI work? Or will it act like a dummy plug and defeat the purpose?

Happy Monday to you all,

/Leovinus

2018 Mac Mini [8th,6C,B] + RX 5700 XT @ 32Gbps-TB3 (Razer Core X) + macOS 10.15.5 [build link]  

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itsage
(@itsage)
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Joined: 5 years ago
 

@leovinus, Does your monitor have multiple inputs? I have done something similar with a 2013 Mac Pro. An HDMI cable connects from the Mac Pro's HDMI port to my monitor's HDMI port while the eGPU uses a DisplayPort cable to the monitor's DisplayPort input. The switching of which graphics card to use is through the monitor input selection.

 

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Leovinus
(@leovinus)
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Joined: 1 year ago
 

@itsage, hiya! I hope you're doing well. Yea I've got the same setup. Thing is, even when I switch inputs on the monitor all the ports are active. So the mini registers it as though I've got two displays running. One over HDMI and one of DP. Which is why I keep unhooking the HDMI cable.

 

2018 Mac Mini [8th,6C,B] + RX 5700 XT @ 32Gbps-TB3 (Razer Core X) + macOS 10.15.5 [build link]  

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itsage
(@itsage)
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@leovinus, I hear you. In macOS, I set the eGPU connected screen to be primary and move the dGPU connected screen to a corner so that my mouse pointer wouldn't get lost. It's nicer in Windows where I could choose to display on the eGPU connected screen only.

 

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ponqable
(@ponqable)
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Joined: 1 month ago
 

@leovinus, I had the same thought about my mini+egpu. solution: the sonnet breakaway has a switch on the power unit, that i use before booting the OS. The monitor gets its signal from the hdmi-port of the mini, so that it just works when egpu is switched off. when booting with egpu on, the intel-gpu forwards the signal from egpu. Needs "Get Info" > "Prefer External GPU" to be switched on.

If your eGPU case has no hardware switch, just use a switchable power cable. That way it saves a bit standby power, too.

p.s.: as my mini got a little hot and thus unstable, i tried and now always use fan control to hold the intel chips a little cooler, which leaves no problems for me..

p.s.2.: windows has no problems which extra cables, so i have a second cable from egpu to 'gaming' monitor.

This post was modified 1 month ago

2012 Mac Mini Server [3rd,4C,Q] + GTX 770 @ 10Gbps-TB1>TB3 (Sonnet Breakaway 550) + macOS 10.15.7 + Win10 (21H1)


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ponqable
(@ponqable)
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@leovinus, as an addendum to yesterdays thoughts:

please check core temperatures when you use egpu and monitor connected directly to mac mini. my best guess (and own experience with my mini+egpu) is that intel chip is throttled when forwarding video stream from egpu to hdmi port, because factory default on system exchaust is VERY low and temperature thus is getting to 100° at which point the clock speed is reduces and system gets 'strange'.

i recommend taking a look at macs fan control which is freely availabe for macos AND (bootcamp) windows. with tis tool you can observe very clearly what happens with egpu connected and - if you decie to do so - to adjust temperature range to a bit more stable values. i set the exchaust based on cpu peci to a range of 50° to 90° (C), which leaves mini quite for the most time but leverages performance significantly on heavy duty.

if you like app - as i do very much - you can purchase a pro license to support the developer

 

2012 Mac Mini Server [3rd,4C,Q] + GTX 770 @ 10Gbps-TB1>TB3 (Sonnet Breakaway 550) + macOS 10.15.7 + Win10 (21H1)


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Leovinus
(@leovinus)
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Joined: 1 year ago
 

@itsage, Yea it's slightly annoying. I'll get a short extension cable for the HDMI and see if it works like I intend it to and report back hehe

 

@ponqable, thank you for your input. As luck would have it I already follow the – what I'd consider best practices – that you mention. I'm just focused on being able to unplug and replug the mini HDMI port via an extension or something so I don't have to reach back behind the mini every time. My eGPU has an on/off switch, so that one is no problem at all.

 

2018 Mac Mini [8th,6C,B] + RX 5700 XT @ 32Gbps-TB3 (Razer Core X) + macOS 10.15.5 [build link]  

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ponqable
(@ponqable)
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Joined: 1 month ago
 

@leovinus, ok then - there are passive hdmi switches that do exactly what you want:

https://www.amazon.com/s?k=passive+hdmi+switch

as the q&a part of the first item suggests these things just seem to switch electical connections between two alternative secondary ports. i would guess then that the inactive port won't 'see' no other connection and thus won't show up as a monitor on the corresponding graphics adapter port.

so, just try it and prove me wrong ^.^

This post was modified 1 month ago

2012 Mac Mini Server [3rd,4C,Q] + GTX 770 @ 10Gbps-TB1>TB3 (Sonnet Breakaway 550) + macOS 10.15.7 + Win10 (21H1)


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joevt
(@joevt)
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Joined: 4 years ago
 

@leovinus, An HDMI extension cable should work (with female connector). It will not act as a dummy display if no display is connected to the extension cable.

A passive HDMI switch would be most convenient. display -> switch -> Mac, eGPU. In either case, make sure cables and switch can handle HDMI 2.0.

 

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Leovinus
(@leovinus)
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Joined: 1 year ago
 

@joevt and @ponqable, thank you both. The switch was a very welcome idea. I'll look into that for sure. Feels better than plugging and unplugging.

 

This post was modified 1 month ago
2018 Mac Mini [8th,6C,B] + RX 5700 XT @ 32Gbps-TB3 (Razer Core X) + macOS 10.15.5 [build link]  

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