Macpro Memory Riser is one the most fragile parts in Macpro, so if you see error usually is resulting from these and not the memory.

Just for information, memory in Macpro Memory Riser have to be in a couple and you can use one memory alone and another common problem will be Macpro Memory Slot Utility Error. Mac Pro users wondering why the Memory Slot Utility keeps appearing at start-up, even if they haven�t upgraded their memory but they can be solve by:

1. In the Finder, open a new window.
2. Either hit Command-Shift-G or select 'Go to Folder' from the Go menu in the menu bar.
3. In the box that pops up on the Finder window, type in: /System/Library/CoreServices/
4. Locate 'Memory Slot Utility.app', right-click on it and select 'Show Package Contents'.
5. In the new window, open the Contents folder and move the 'Info.plist' and the 'version.plist' files to another location, such as the Desktop.
6. Close all the open windows and reboot the computer.

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