maximum VGA resolution on mac mini

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Level 1

4 points

maximum VGA resolution on mac mini

Hello.

We bought a mac mini to run experiments with an old SONY trinitron CRT. Before we used an old mac pro with a DVI to VGA adapter and could go up to 1280x960 at 100Hz. Now, with the new mac mini (2.6GHz model) and mini-display to VGA adapter, we can go only up 90Hz at 1280x960 (and it wasn't even in the default system settings). If we go down to 1280x768 or 1024x768, we can increase the refresh rate to 100Hz but then the resolution is a bit too low for us.

So why can't we use the same resolution and refresh rate as before? The monitor and VGA cable can handle the resolution. Is the limitation coming from the graphic card of the mac mini? If that's the case it's pretty terrible. Is it coming from the mini-display port? Then why use a port that have a lower resolution than the antiquated VGA technology? Is it a limitation from the mini-display to VGA converter? If yes, what are the workaround?

Thank you very much.

Regards,

Baptiste

Mac mini, OS X El Capitan (10.11.3)

Posted on Feb 16, 2016 7:36 AM

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Answer 1

Feb 16, 2016 11:57 AM in response to baptisteC

Not sure to be honest. I have the 2014 model with the 2,6 GHz CPU. I'm running a dual screen setup 2x 1920x1080 digitally, and it's running superbly. Maximum supported is 2x 2560x1600 for our Mini according to the manual.

My guess would be that your Sony CRT and the Intel Iris Graphics chip don't like each other very much.

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Answer 2

baptisteC Author

Level 1

4 points

Feb 16, 2016 12:05 PM in response to SandsOfArrakis

Thanks.

Are you using a mini-display to VGA adapter on your monitors?

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Answer 3

lllaass

Level 10

210,513 points

Feb 16, 2016 12:34 PM in response to baptisteC

Could be due to the limitation of the Mini.

What specific Mini?

I have no problem with 1920x1080 on my 2012 Mini using a mini displayport<VGA adopter

Try using an like like:

SwitchResX _ Resolution Control For Mac

For using SwitchResX with EC see:

http://www.madrau.com/support/support/srx_1011.html

Display Menu from Mac App Store

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Answer 4

baptisteC Author

Level 1

4 points

Feb 16, 2016 4:12 PM in response to lllaass

Thanks. We will give SwitchResX a shot.

We are trying to identify what the bottleneck is and how to bypass it. We know the monitor can go higher as we used it at higher resolution with the 10-years old power mac. So it's either because the mac mini blocks some resolutions (it accepts higher bps at 60Hz so why does it matter that it is 100Hz at lower resolution?), or the mini-display to VGA adapter is lowering the bit rate.

Also I tried a 144Hz ASUS display and it couldn't run it at high frame-rates either so it looks like the mini-display is a pretty terrible technology. I wonder why Apple tries to put it everywhere.

Baptiste

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Answer 5

Feb 17, 2016 8:49 AM in response to baptisteC

Both my screens are hooked up digitally. One with an HDMI cable, the other with a HDMI -> mini display port (thunderbird) cable.

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Answer 6

Lanny

Level 6

13,225 points

Feb 17, 2016 3:22 PM in response to baptisteC

You haven't identified the model of your Mac Pro or your MacMini, so no one could possibly provide you with accurate information. But, yes, an older Mac Pro could easily have a better graphics capability than and a newer Mac Mini. Keep in mind, despite whatever their age difference, you're comparing the graphics capabilities of Apple's top of the line desktop to their least expensive, lowest performance desktop.

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Answer 7

baptisteC Author

Level 1

4 points

Feb 17, 2016 4:41 PM in response to Lanny

Hi.

As stated above, we have a mac mini 2014, the 2.6GHz model (and 16Go RAM). Isn't that the model? You are right that the graphic card might be better on the power mac G5 than on the mac mini despite the almost 10 years age difference. My concern is that the graphic card of the mac mini can handle a higher BPS than what we want. But it won't get to 100Hz. What I want to know is whether mac minis can't reach 100Hz in any case (for example it seems that they can't run monitors at 144Hz, and that's a software issue as windows can with the same graphic card). Or if the mini DisplayPort to VGA adapter prevents it. It might be both. I found this on the apple FAQ about the adapters:

"VGA displays that use higher refresh rates (such as 85 Hz) at resolutions of 1600 x 1200 or greater may not generate video properly until you lower the refresh rate."

So it looks like there are limitations imposed by the adapter. We'll try SwitchResX as suggested by lllaass, but I doubt it will do us any good. I think the mac minis have just been designed to handle very high res monitor at slow refresh rates.

Cheers,

Baptiste

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Answer 8

lllaass

Level 10

210,513 points

Feb 17, 2016 4:48 PM in response to baptisteC

The graphics on the 2.6 GHz Min is better than the G5.

Todays LCD monitors really do not need the higher refresh rates that older CRT monitors.

Why do you want/need 100 Hz?

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Answer 9

baptisteC Author

Level 1

4 points

Feb 17, 2016 4:55 PM in response to lllaass

We do experiments to study motion perception so we need high refresh rates. And we occasionally display color stimuli that's why we need CRTs.

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Answer 10

lllaass

Level 10

210,513 points

Feb 17, 2016 5:14 PM in response to baptisteC

This provides some info even if for the 2012 Mini

Mac mini supported resolutions and refresh rates

You might try changing the EDID

https://gist.github.com/ejdyksen/8302862

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Answer 11

baptisteC Author

Level 1

4 points

Feb 18, 2016 11:14 AM in response to baptisteC

Ok. I solved the problem.

I found out the pixel clock of the graphic card is limited to 165MHz on mac minis. The limitation is from the OS. Installing SwitchResX, despite being a very nice software, did not help. I could set any resolution and FPS I want as long as it was under ~160MHz, which breaks down, annoyingly, to about 97Hz at 1280x1024.

However there are patches that can remove the pixel clock limitation (this one for El Capitan: https://github.com/Floris497/mac-pixel-clock-patch), and then I could set up a refresh rate of 100Hz from the normal system preferences display panel. No need for SwitchResX. I checked the inter frame interval and it was quite accurate (10.01±0.05 msec).

Thanks for the help.

Regards,

Baptiste

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