I won't claim to have any more experience than any other user here. Most here are experts in their own right. I am not a hobbyist either. I have worked with Photoshop and the Macintosh platform for about 20 years, since version Photoshop 3/Illustrator 88/Aldus Pagemaker. All I can speak about is my experience. My 2006 MacPro with dual nVidia 8800GT cards, 3 monitors, OS 10.5.8 or 10.6.4, and Photoshop CS5 was a COMPLETE nightmare. Unlike any previous Adobe application that has ever been installed here. As I've posted MANY times... I wiped drives, reconfigured the video cards... did EVERYTHING that could be done and nothing allowed Photoshop CS5 to run smoothly on the 2006 MacPro. It was only after swapping hard drives with a 2010 Mac Pro that Photoshop CS5 will now run smoothly on the 2006 MacPro. Now, my first inclination is perhaps I had bad sectors on the hard drive itself. However, that was all checked and verified via Disk Utility many times. Additionally Installing 10.6.4 and Photoshop CS5 on a completely different hard drive inside the same 2006 MacPro did not correct the Photoshop CS5 issues. Perhaps there's a firmware/install issue on the 2006 MP? Or an installer issue? Who knows. I didn't want to upgrade from 10.5.8. 10.6 has issues still. I was forced to upgrade with the new 2010 MacPro - no choice. And while I'm still trying to work around other issues 10.6.5 presents, it does appear to have cleared the Photoshop CS5 issues I was having. From my experience, I have clearly come to the conclusion that there is something about my 2006 Mac Pro and OS10.6.4/10.5.8 that Photoshop simply does not like. Whether the issue is created upon installation, is due to my dual video cards, or large monitors, or something else remains a mystery to me. When I get my replacement 2010 MacPro back from Apple, I'll swap drives again and just for my own curiosity attempt to install OS10.6.5 and Photoshop CS5 on the 2006 MacPro directly (rather than swapping drives) to see if it functions then. I'm guessing it won't and the error or issue is in place with the install on the system. Edit to add... I don't run any PPC apps anymore at all.
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