Hi Peter,

 

No, only newer machine is a Macbook Air which, aside from being with Georgie in 
Perth at the moment, only has USB3 ports. So no other way to test the same 
monitor/lead setup.

 

But, I’m pretty sure it shouldn’t be the older OSX since the machine, as 
bought, supposedly supported video output up to 2560x1600 through the mini 
display port and it came with SL 10.6!

 

 

However, since Officeworks is a 15 minute walk, and since I value my ever 
diminishing time on this earth, I may pass on saving a few dollars waiting for 
Amazon and just buy the lead and see if it works!

 

Sometime later ……     Well, that DID work!!

 

Both iMac and external monitor are now set at 2560x1440 and, interestingly, the 
monitor display also seems much crisper and cleaner with the new cable.

 

Also, a quick systems report now shows that the iMac recognises the display as:

LEN D32qc-20:

  Resolution:       2560 x 1440 @ 60 Hz

  Pixel Depth:     32-Bit Color (ARGB8888)

  Mirror:               Off

  Online:               Yes

  Rotation:           Supported

  Connection Type:          DisplayPort

  Television:        Yes

 

So, now I’m a happy camper and, even though the monitor only has the same 
resolution as the iMac screen, the larger physical size means I don’t need the 
same zoom level on Excel spreadsheets and so see more of each worksheet.

 

The lesson learned is:

If you want to drive an external monitor from an older Mac with a mini display 
port  output you will get MUCH better results with a mini display port to 
display port cable than with a mini display port to HDMI cable.

 

 

 

Cheers

 

 

 

 

Neil

 

From: <wamug.org.au-wamug-boun...@lists.wamug.org.au> on behalf of Peter Crisp 
<petercr...@westnet.com.au>
Reply-To: WAMUG <wamug@wamug.org.au>
Date: Friday, 25 March 2022 at 14:26
To: WAMUG <wamug@wamug.org.au>
Subject: Re: [WAMUG] Cannot get external monitor to display full resolution

 

Hi Neil, I read this with interest as I too have found the adaption of external 
monitors with Mac’s a bit hit and miss. 

 

As a test, do you have on hand a late model Mac/Macbook you could see if the 
later OSX is smarter in this sense and how it recognises the external monitor 
when you plug it in using the leads you currently have and get the quick 
systems report for the connected monitor. Your 2009 Mac is certainly high spec 
but by being 2009, it is held back to older OSX versions and perhaps this may 
be the issue. You may have to get yourself a late model iMac but I wouldn’t 
resort to that yet.

 

Pete.

 

On 25 Mar 2022, at 1:48 pm, Neil Houghton <n...@possumology.com> wrote:

 

OK, here is the iMac setup:

 

Late 2009 27” iMac – top configuration, 2.8 GHz core i7, Graphics ATI Radeon HD 
4850 512 MB

iMac has been reconfigured with 250 GB SSD, 3TB internal drive and currently 
20GB RAM

Currently running El Capitan OSX 10.11.6

 

With the SSD and RAM upgrade this is still pretty snappy and I am frequently 
running multiple Excel spreadsheets and/or multiple browser windows with many 
tabs in each – which took me to a second monitor.

 

For a while I had a 27” full HD 1920x1080 monitor running, which all worked 
fine but I found the discontinuity of tracking from the 2560x1440 iMac screen 
to the 1920x1080 monitor screen sufficiently annoying that I ended up reducing 
the iMac resolution to 1920x1080 to match the monitor – which I found much more 
useable.

 

However it seemed a shame to have to resort to downgrading the iMac resolution 
– so, given that the iMac can support video output up to 2560x1600 - I decided 
to upgrade the monitor!

 

I found a good deal on a 31.5” monitor with 2560x1440 resolution – the same as 
the iMac native resolution this was the product (though it was only $355 when I 
bought it)

https://www.amazon.com.au/gp/product/B08J3S6BT4

 

I was pretty happy when after promising delivery by March 30 to April 11 they 
actually delivered it yesterday – 2 days after I ordered it!

 

So all setup and ready to go – and it is all working fine EXCEPT, despite the 
monitor having 2560x1440 resolution,  the maximum resolution offered in  the 
OSX display preferences is 1080i, ie 1920x1080 and a quick systems report shows 
that the iMac recognises the display as:

LEN D32qc-20:

  Resolution:       1920 x 1080 @ 60Hz (1080i)

  Pixel Depth:     32-Bit Color (ARGB8888)

  Mirror:               Off

  Online:               Yes

  Rotation:           Supported

  Interlaced:        Yes

  Television:        Yes

 

In my setup the monitor connection is by a direct mini display port to hdmi 
cable (no adaptors) as this was readily available when I bought my previous 
monitor.

 

I have googled this and find that this is not an uncommon problem and not 
specific to any particular monitor but seems to be a problem with the Mac 
recognising the availability of the higher resolution of an attached monitor. 
People seem to have mixed success in resolving this problem but some seem to 
have more luck with Display port connections, rather than hdmi, recognising 
higher resolutions and this monitor does have a display port input as well as 
hdmi.

 

So, I guess, the question is – does anyone have any experience of driving 
higher resolution monitors from older imacs? Is buying a new cable such as this:

https://www.amazon.com.au/Rankie-DisplayPort-Cable-Resolution-Ready/dp/B00YOQYQWY

or this:

https://www.officeworks.com.au/shop/officeworks/p/comsol-displayport-to-mini-displayport-4k-cable-2m-comdpdp020

 

likely to solve my problem?

 

Any feedback gratefully received!

 

Cheers

 

 

Neil

 

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