My late 2009 iMac has a screen that goes dark from time to time. It’s annoying and was my major decision factor to not buy a new one when I upgraded my computer. Except for the ultrawide monitor, all of my displays are now 4K which weren’t compatible with High Sierra. So can I use a 4K display as a second monitor? The answer is yes we can America.
Since I picture says more than a 1000 words, let’s start with this one.

Late 2009 iMac 4k display settings

late 2009 iMac 4k display settings
Late 2009 iMac Catalina display settings

How can a late 2009 iMac use a 4k monitor

Those who expressed skepticism were sort of correct. A regular iMac would not be able to power a 4K monitor but after upgrading to Catalina, my late 2009 iMac was able to do just that. If you look at the refresh rate, you see that it will not manage a 60 Hz refresh rate. The highest it can go is 30 Herz. Again, for a 11+ year old iMac with a 512 MB AMD graphics card, that is nothing short of amazing.

How does Catalina look and feel on a 4K screen running at 30 Hertz?

Before my Catalina experiment, I have heard of but never used a display with a 30 Hz refresh rate. But honestly, for web browsing, web design, e-mail, Pixelmator and programs similar to those, it is not much of an issue. I can move the browser window across the screen and don’t see any ghosting. Is it as smooth as moving windows on my Dell Linux workstation which has an 8Gig Gfx card? No, but again, this very old iMac was a trough away until yesterday so I can live with it.

If there was an easy and quick option to remove the hard drive, I would have recycled it years ago. Now I am seriously considering to buy a cheap SSD from Amazon and enjoy it a few more years.

To patch or not to patch

The key to extending the life of an old iMac is evaluating the risk of upgrading it to Catalina. For me it was a easy decision because the machine was no longer used except for picking some assets off of the hard drive once in a blue moon. After I run the patch and installed Catalina, I instantly knew that all the YouTube videos were real. Many have done this and overall, their experiences mirror mine.

Lastly, I should also mention that I lost the target display mode advantage. Ever since I upgraded to Catalina, the monitor no longer switches to target display mode. I am OK with that because I have plenty of monitors and running a whole operating system just to use a monitor isn’t my thing.

To learn more about installing Catalina on unsupported Apple computers, simply search and you shall find plenty of posts that provide the goods. If I knew that linking to the patch file is legal, I’d do it but as they say: “google is your friend” (sort of). Thank you for reading.

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