So started building up my G5 tower with MorphOS and then saw one of the sweet 30" Apple Cinema Displays that do 2560x1600. Problem is, MorphOS showed the resolutions for the 9600 I had in the machine, but it wouldn't actually let me select them and run it at that resolution. Came to the conclusion that the 64mb card in there was not quite enough to do it...

Well today I got the 256mb version of basically the same card. And while I can click on Edit on the 2560x1600@24bit resolution and then click Test and it will show it. It refuses to actually run the computer in that resolution!

MacOSX (Tiger 10.4.11) is running at that resolution just fine after installing the ATI/AMD drivers onto the system (for some weird reason MorphOS would read the CD, MacOS would not, and I ended up having to copy it to a USB stick from AMD's website...

All I can get in MorphOS is a 'you need to reboot to show new screenmodes' (or something like that) but it shows all of them, I just can't apply them. Really odd.

Any help appreciated.

64 and 128MB versions lack the Duallink-DVI port needed for that res at 60Hz. OSX can and will clock that down to 30Hz on a Singlelink-DVI MorphOS won't/can't.

So....

- make sure you have a genuine Apple 9600, flashed PC cards won't do

- check if your connected to the right port or are running at 30Hz in OSX (only 1 port on that card has Duallink)

Definitely connected to the right port, as the other port only shows up to 1280x800 in MacOS.

The card I have is an AGP PC&MAC Edition 9600 Pro with 256mb. Weird thing is, the ATI Radeon tools won't show the refresh rate. It just says 'Refresh Rate --'. Not sure where else in Tiger I can check. But for sure in MorphOS it sort of knows what to do with it, as pressing Test on the resolution will show the full resolution (a little flickery) but won't let me save it there...

The PC&Mac-Edition isn't the same card as the 9650 that shipped with 2.7GHz G5s which is known working.

I do have 256MB 9800PC&Mac which I haven't really used that much as it has mechanical issues, but when I had it in the the QS G4 I was also unable to use a 2560x1440 mode and some research suggested that it does not have a DualLink output. So it stands to reason that this might also be true for the 9600.

Why it goes down to 1280x800 on the 2nd port......

It's been a decade since I fiddled with PPC OSX (and even more for Tiger), but you might want to try this:

- select "about this Mac" from menu
- click system information
- check GFX/displays