Advice on flaky ATI Radeon HD 2600 XT 256 MB in MacPro (early 2008)

[epidote]

Looking for a fix to a stock graphics card that is sometimes recognized by MacPro (early 2008) on boot, and works fine, but needs reboot if not seen. As seen from screen sharing graphics info in "About this Mac" is blank.

Current card is a ~2 y.o. replacement to stock ATI Radeon HD 2600 XT 256 MB

The old card was faulty and would cut out after a few minutes, but this one works fine until shutdown, then is sometimes seen, sometimes not.

Time for a new card or is there a fix I should try?

Any ideas appreciated or do I just go..
https://forums.macrumors.com/threads/1656298/

Running 10.8.5 but have Mavericks on another internal that seems to work fine if need be, just don't like the "no single window spread across multiple screens", BTW can that be turned off?

 

[Ledgem]

Running 10.8.5 but have Mavericks on another internal that seems to work fine if need be, just don't like the "no single window spread across multiple screens", BTW can that be turned off?

I can't really advise you on the graphics card. Based on your description, though, I'm curious as to whether it's really the graphics card, or the slot on the motherboard that it's connected to.

Regarding the question that I quoted, yes, you can disable that behavior. In System Preferences > Mission Control, uncheck "Displays have separate Spaces." Note that this will return multi-display behavior to the way that it was in OS X 10.8 and earlier.