Display not working

[nickbwi]

Hello Everyone,
So I have a 2011 Mac Mini Server, and I have it hooked up to my LG 34" Ultrawide gaming monitor w/144mhz refresh rate. I had been using a 1080p only mini display port to HDMI cable and would only get the 1080p option in my Display options. So I found and bought a 4k mini display to HDMI and can now get my beautiful 2560x1080 resolution as an option. Now to my issue, upon changing my resolution to my native display, I noticed the 144mhz under the refresh tab, and thought sweet 144mhz, well me not thinking I selected it and well the cable apparently doesn't support it and now i get a squiggly lines and no picture. I can't figure out how to get it so I can get back to the options so I can change the refresh rate back to 60mhz. I've tried the get into Safe mode which it won't, and tried reseting the NVRAM and got me what seemed to be progress, but alas NOPE. Any ideas what I could try. would switching to a HDMI out and unplugging the mini display port give me the chance to change the refresh rate and then go back to a mini display cable again? I appreciate any help or ideas.

Nick ...

 

[Rod]

So you can't see System Preferences to change the display settings? Sorry to say I don't have a lot of knowledge in this area but it's clear you need to be able to see the display somehow if not on that monitor then one that can read the settings you currently have. Luckily the Mac Mini is fairly portable so I'd suggest you take it to a computer repair store (preferably a Mac one). hook it up to a display capable of handling 144mhz and change the settings back. Sorry if that's not very helpful, maybe someone else will chime in with an easier technique.

 

[chscag]

Welcome to our forums.

There is no way that you chose a refresh rate of 144 MHz or for that matter 60 MHz. A refresh rate of 144 Hz and 60 Hz, I would believe.

I'm sure you got your Hz wrong.... but in any event, try following what Rod recommended.

 

[Horsa]

I'm curious to know why the machine won't boot into Safe Mode (Power up / press and hold down the shift key until the apple logo appears). I would have thought that Safe Mode would output a very basic, universally-compatible video signal that any cable/monitor combo could cope with, thus enabling you to re-set the refresh rate to something sensible.

What actually happened when you tried to boot into Safe Mode?

Just a side note: I'm really surprised such a thing can occur with modern digital video interfaces, as even back in the days of (full) VGA, the monitor would tell the graphics card what resolutions and refresh rates it was capable of displaying and limit the modes you could choose. If you did try to output an incompatible signal to your monitor, the screen would go black for a few seconds before the system defaulted back to something that worked. Go figure...

 

[chscag]

Back in the days when we were using CRT displays, a higher than recommended refresh rate could actually cause damage to the display. Much less chance of that happening with modern LCD displays which normally accept a refresh rate of 60 Hz.

In any event LG has discontinued that particular display. And its specs do say it can accept a refresh of
144 Hz which would be primarily for fast gaming. It really doesn't matter because his 2011 Mini does not support that high a refresh rate.

 

[nickbwi]

Yes my monitor does support 144Hz refresh rate, as its my PC gaming monitor. It's funny that the option showed up under the refresh rate so I was like awesome, I obviously don't game on a Mac mini especially one that old with integrated graphics, but I thought a nice extra smooth experience. There are multiple issues with it, 1) cable doesn't support it, 2) Display port does support 144Hz refresh rate, however any HDMI below 2.0 does not, (which 2.0 was in very limited on things if anything at the time this monitor was released), you HAD to use display port to get the higher refresh rate.

Not sure why it wouldn't boot into SAFE mode, but it looked like it would then it just continued onto OS X with no picture or have the squiggly lines.

Any any rate here is a screen shot of my HZ choices so you can see that it does give me many options to choose from. This is not from the Mac mini in question this is my other one I have.

Back to the matter at hand. I did manage to fix the issue on the 2011 mac mini. And just as I suspected what I thought would work, worked. So mini-display port and HDMI out work individually. So in other words they had different settings for each port. I finally found a HDMI cable and plugged it in the back on the Mac mini at the same time as the mini-display and I then unplugged the mini-display port from the monitor and plugged in the HDMI and the picture came up. I went to the display settings and left the settings up. I unplug the HDMI from the monitor and quickly plugged in the mini-display port cable back in and before it could mess up I click on 60hz and clicked on "default for display" and then the screen flashed and went to 1080p resolution. Restarted and it allowed me to select 2560x1080

 

[chscag]

Yes my monitor does support 144Mhz refresh rate, as its my PC gaming monitor.

Your monitor and none that I know of supports a refresh rate of 144 Mhz! Your monitor can support a refresh rate of 144 Hz. See the difference? Your screen shot clearly shows this.

LG 34UC79G-B 34 Inch 21:9 UltraGear™ Full HD IPS Curved Gaming Monitor (34UC79G-B) | LG USA

Get information on the LG 34UC79G-B 34 Inch 21:9 UltraGear™ Full HD IPS Curved Gaming Monitor (34UC79G-B). Find pictures, reviews, and tech specs.

www.lg.com

Note the refresh rate.

Anyway it seems you resolved the problem.

 

[Horsa]

Glad to hear that you've resolved the problem, @nickbwi. As @chscag points out, though, you do need to get your head round those abbreviations. For future reference:

Hz = Hertz (cycles per second)
kHz = kiloHertz (thousands of cycles per second)
MHz = MegaHertz (millions of cycles per second)
GHz = GigaHertz (billions of cycles per second)
...etc

 

[Rod]

Bit of a tricky solution but well done fixing it.