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Connecting Mac Pro4.1 to LG Ultrawide monitor.

P

Peter Triangle Wave

macrumors newbie
Original poster
Aug 23, 2018
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Hi Forum,
having problems connecting my Mac Pro4.1 to a new monitor. Using the original installed graphics card I got with the Mac from new. The graphics card is a Nvidia GT 120, has a mini DisplayPort and DVI dual link output . The monitor is a LG Ultrawide one and only has HDMI 1.4 inputs. Its not a 4K monitor. I am using the mini DisplayPort output to connect to the monitor via a mini DisplayPort to HDMI adapter. I think the adapter is passive. The monitor works but when the monitor aspect is in any of the wide screen modes the image looks tubby,slightly stretched or squashed. Display resolution on the the mac is 1080p. Have been in contact with my local Apple Store,local Mac resellers and computer stores,all of which given different suggestions to solve the problem. I do not want to install a different graphics card in the Mac Pro at the moment as I am using two different OS on the machine (Snow Leopard and El Capitan) and a newer card may not support Snow Leopard. LG said the monitor should work with the Mac and its graphic card. Asked them before I brought the monitor. I know nothing about video formats. But have been reading up about them. But have no practical experience of the different format and standards. Any help or suggestions would be great.

Peter
 
What model is your monitor? Seems very odd to me that an ultrawide would only have HDMI inputs. There's no displayport?

You might have better luck with a dual-link DVI->HDMI adapter. IMHO DisplayPort is just a problematic, picky "standard" in general. DVI and HDMI are the exact same signal, so the corresponding adapters are very simple, passive devices that "just work".
 
Thanks for you replies.
Monitor model is a LG 29WK500 and the specs state its resolution is 2560 x 1080. As the DVI output on the graphics card is a dual link one could I just use a DVI dual link to HDMI cable,making sure the cable is wired for dual link use,Bookemdano. Or is it all a waste of time as h9826790 says.
I emailed LG before buying the monitor with the specs of my Mac Pro and the installed graphics card. They sent me back a list of monitors that would work with the card and my Mac Pro. I choose this one because it has no speakers in it. Do not like speakers in monitor. Never use them. I am thinking of sending the monitor back and getting one with DisplayPort inputs (even if its has built-in speakers) if I cannot get the problem sorted by the middle of next week. But as h9826790 says I could have the same problem. Looking at the spec for the graphics card its maximum digital resolution is something like 2560 x 1600. Going to look some similar threads I just found.

Many thanks,

Peter
 
Interesting read! :(
Contacted Nvidia support regarding the max digital resolution for the GT 120 card. According to them 2560 x 1600 is only available by the dual link DVI-I output. The mini DisplayPort will only output 1920 x 1080.
Look like I will have to send the display back and choose a different one. Options would be either be a 27inch display using 1920 x 1080 (which I know will work) or if I wanted a 29inch screen ultra wide display,one with DVI inputs. Would have to really check if the second option would work first before buying. Changing the graphics card in my Mac Pro to one that supported 2560 x 108 would mean I would not be available to use Snow Leopard. Is that right. Using Snow Leopard and El Capitan on the Mac Pro at present.

Peter
 
Peter Triangle Wave said:
Interesting read! :(
Contacted Nvidia support regarding the max digital resolution for the GT 120 card. According to them 2560 x 1600 is only available by the dual link DVI-I output. The mini DisplayPort will only output 1920 x 1080.
Look like I will have to send the display back and choose a different one. Options would be either be a 27inch display using 1920 x 1080 (which I know will work) or if I wanted a 29inch screen ultra wide display,one with DVI inputs. Would have to really check if the second option would work first before buying. Changing the graphics card in my Mac Pro to one that supported 2560 x 108 would mean I would not be available to use Snow Leopard. Is that right. Using Snow Leopard and El Capitan on the Mac Pro at present.

Peter
Click to expand...

Well I have no idea if it will solve your problem, but dual-link DVI to HDMI adapters are cheap and might be worth a try. But as h9826790 said, the problem may be more that the GT120 won't do ultrawide resolutions, even if they are under the max 2560x1600 the card is capable of. I have no idea. But for $6 you can find out:

https://www.amazon.com/Fullink-Gold-Plated-DVI-D-Female-Adapter/dp/B00MCSMVYG
 
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Peter Triangle Wave said:
Interesting read! :(
Contacted Nvidia support regarding the max digital resolution for the GT 120 card. According to them 2560 x 1600 is only available by the dual link DVI-I output. The mini DisplayPort will only output 1920 x 1080.
Look like I will have to send the display back and choose a different one. Options would be either be a 27inch display using 1920 x 1080 (which I know will work) or if I wanted a 29inch screen ultra wide display,one with DVI inputs. Would have to really check if the second option would work first before buying. Changing the graphics card in my Mac Pro to one that supported 2560 x 108 would mean I would not be available to use Snow Leopard. Is that right. Using Snow Leopard and El Capitan on the Mac Pro at present.

Peter
Click to expand...

HD4870 can drive ultra wide display natively in Snow Leopard and El Capitan on a 4,1.
[doublepost=1535234064][/doublepost]
Squuiid said:
That will be one horrible display. 27” is far too big for 1920x1080 IMO. Those pixels will be huge and rather noticeable.
2560x1600 or 2560x1440 is without a doubt the res to go for at that size.
Something like this...
https://www.amazon.co.uk/gp/aw/d/B00M913DVG/
Click to expand...

TBH, I prefer 1920x1080 (~80ppi) much more than 2560x1440 (~110ppi) for 27” monitor.

Because my viewing distance usually about 80cm away from the monitor, 110ppi makes the text too small. It cause me often need to lean forward to read. But 110ppi also not good enough to use 1080p HiDPI (everything will looks burry).

In my case, 80ppi running on a 27” monitor is just right. Of course, much much less desktop space to use if compare to 2560x1440. But I can go for 49” 3840x1080 to double the space. I am very very happy with this “large pixel” setup now. Much more comfortable to use than my 27” ACD.

Of course, the best is still 4k for 27” (~160ppi). So that, not matter the use prefer 1440p or 1080p, can always be done well with HiDPI.

And I can imagine, if the normal viewing distance is 50cm or less, 80ppi definitely won’t look good.
 
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Peter Triangle Wave said:
Interesting read! :(
Contacted Nvidia support regarding the max digital resolution for the GT 120 card. According to them 2560 x 1600 is only available by the dual link DVI-I output. The mini DisplayPort will only output 1920 x 1080.
Click to expand...

The MiniDP will do at least 1920x1200, and I’d be surprised if it can’t do 2560x1440.
 
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mattspace said:
The MiniDP will do at least 1920x1200, and I’d be surprised if it can’t do 2560x1440.
Click to expand...

This is from a Hackintosh, but doesn't really matter. The Apple GT120 clearly can drive a 27" Apple Cinema Display at 2560x1440 via the mini display port in macOS.
image.png
 
So even though 2560x1080 is almost a million less pixels than 2560x1440, the GT120 can display the latter but not the former? I guess it's just because it doesn't "understand" any ultrawide resolution, no matter how many pixels?
 
bookemdano said:
So even though 2560x1080 is almost a million less pixels than 2560x1440, the GT120 can display the latter but not the former? I guess it's just because it doesn't "understand" any ultrawide resolution, no matter how many pixels?
Click to expand...

Correct, at least not natively. I never try something like SwitchResX, but my GT120 never go beyond 1920x1080 on my 3840x1080 display. Even I config my monitor to work as 2560x1080 + 1280x1080 to accept two inputs and display them side by side. GT120 still won't go beyond 1920x1080 on the 2560x1080 side.

I must emphasis that I only spend very little time on this kind of test. So, I can only say it won't work natively. But I am not 100% sure if there is any work around exist.
 
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bookemdano said:
Well I have no idea if it will solve your problem, but dual-link DVI to HDMI adapters are cheap and might be worth a try. But as h9826790 said, the problem may be more that the GT120 won't do ultrawide resolutions, even if they are under the max 2560x1600 the card is capable of. I have no idea. But for $6 you can find out:

https://www.amazon.com/Fullink-Gold-Plated-DVI-D-Female-Adapter/dp/B00MCSMVYG
Click to expand...

Did try this out today and got the 2560 x 1080 resolution option appear in the system display preferences. Selected it and screen went blank. Was using El Capitan 10.11.6. Do not know if I should exchange the monitor for the one with DVI-D inputs or try upgrading the GPU.

Peter
 
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Peter Triangle Wave said:
Did try this out today and got the 2560 x 1080 resolution option appear in the system display preferences. Selected it and screen went blank. Was using El Capitan 10.11.6. Do not know if I should exchange the monitor for the one with DVI-D inputs or try upgrading the GPU.

Peter
Click to expand...

Well as h9826790 pointed out, you can buy a used ATI HD4870 (they're pretty cheap on ebay, $50-60). That is a more powerful card that will work with Snow Leopard and El Capitan (even up to High Sierra, but not Mojave). According to him it does work with ultrawide resolutions like your LG uses. But it doesn't have an HDMI port either, so you'd need to adapt the miniDP or DVI to HDMI to plug it into your LG.

Here's a listing of Mac Pro 4870 cards on ebay. Note that unless you find a listing that includes them, you would also need to purchase two mini-6-pin PCIe to 6-pin PCIe cables to power the card (like this: https://www.amazon.com/Mini-6-pin-Video-Power-Cable/dp/B075W4QXVL)

If you're not in love with that monitor and can still return it, then you can do that and instead buy something that has a better array of inputs. But if you buy another ultrawide it probably still won't work with the GT120, so if you really want ultrawide you should upgrade the GPU anyway.

If you can do without 10.6 compatibility then you can buy a brand new and more modern GPU with a full array of ports and compatibility with every common resolution. Is there any reason you can't just use Parallels or VMWare to run Snow Leopard?
 
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I sent the monitor back and got another 29 inch ultra wide display from LG,but with DisplayPort,HDMI and DVI-D inputs. Connected the dual link DVI-I output on the GT 120 graphic card to the DVI-D input on the monitor and it worked. Screen looks great. No distortion of image as before. Got the 2560 x 1080 resolution setting in the display preferences for the LG monitor. Nvidia support said that the 2560 x 1080 resolution is only available on the DVI-I output from the card and the DVI-I output will drive a 29 inch ultra wide screen. The mini DisplayPort output on the card will support high resolutions but not the full 2560 x 1080 required by a ultra wide screen. Thanks to everybody for their help and suggestions.

Peter
 
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