How to Fix OS X 10.5.7 DVI-HDMI Screen Resolution Issues

Apple (s aapl) had finally released OS X 10.5.7, so I downloaded the combo updater in preparation to install on my three Macs. After installing the update on my MacBook Pro and my wife’s iMac without any issues, I ran the combo updater on my Mac mini that’s hooked up to my TV.

My TV’s native resolution is 1360×768 and ever since I got the Mac mini, this has worked flawlessly and with an extremely crisp picture when using a DVI-HDMI cable. So it was to my dismay when, after installing OS X 10.5.7 and the mini rebooted, the resolution displayed was completely wrong. “Ah, it must have reset, I’ll go change it back,” I thought to myself. So I went to the Display preference pane in System Preferences and looked for 1360×768, but it wasn’t there. I blinked and looked again; it still wasn’t there.

I tried all the other various resolutions, such as with the over-scan option turned on and then again with it turned off. Nothing looked right or displayed properly, and I was aghast. My wife would be wanting to watch the latest episode of “Master Chef” being recorded by EyeTV later in the evening and she wouldn’t be happy to hear that I had done something to the setup that was working excellently before I “fixed something that wasn’t broken and broke it.”

So I started searching and found that this is a common issue caused by the 10.5.7 upgrade. Quite simply, it seems that the DVI supported resolution detection is now broken. Apple is apparently aware of the issue and its developers are looking into it — but there’s no word on an ETA for a fix. If you have a Mac that you regularly hook up to your TV via DVI-HDMI, it would be advisable to stay on 10.5.6 for now.

In the meantime, if the horse has already bolted before you shut the stable doors and you’ve already upgraded, there are two workarounds that you can do to restore your TV’s native resolution.

1. Go back to VGA
If your TV has a standard PC VGA input, you can use a DVI-VGA adapter instead of DVI-HDMI. This will make the correct resolution available again in the Display preference pane. Of course this goes backwards in technology to an analog signal, but it will still look better than the wrong resolution. This is what I’ve done for now — my wife can’t see the difference between VGA and HDMI anyway, so she’s happy.

2. Use ScreenResX to get your resolution back
A useful utility called ScreenResX can be installed. This lets you customize and tweak which resolutions are available in the Display preferences (even creating custom resolutions as required). ScreenResX is available as a 10-day trial and the good news here is that once you’ve created the new resolution and made it available in the Display preferences, you can uninstall ScreenResX.

To keep up-to-date on this issue, keep an eye on this discussion thread on the Apple support forums. This also lists various ScreenResX settings people have used to get their resolution back, so is a useful reference point to assist with this. Hopefully Apple will fix this issue soon, as it does great damage to its “It just works” motto.