Monitor resolution not right on 30 inch Apple Cinema Display

[dwight_talley]

I just finished installing High Sierra with an ATI Radeon 570 8gb video card connected by display port to a Apple 30 inch Cinema display. High Sierra sees the monitor and knows that it is a 30 inch Apple display. However, the only resolution is 1280x 800. It should be 2560x1600.

What is the simple fix? I have done numerous searches but got lost in the fixes.

Thanks

Dwight

 

[dwight_talley]

Well, after much testing and reloading and so on I gave up. I loaded windows on the computer and the display port only allowed a resolution of 1280x800. Connecting to the DVI port I got full resolution. So it was the port restrictions that was causing the problem. However, when loading High Sierra, the output switches from DVI to DP. Don't know how to stop this. If I put a monitor on each, DVI and DP, there is no image at all.

Anyone know how to stop the display from switching from DVI to DP???


Dwight