Mac Pro (8-core): Memory and hard drive compatibility; system identification
Quad-core Mac Pro memory is not forward-compatible with the 8-core Mac Pro.
Memory and hard drive compatibility Apple has published a Knowledge Base article explaining RAM and hard drive compatibility for the 8-core Mac Pro. Essentially, parts shipped with and for the 8-core Mac Pro are backward-compatible with quad-core Mac Pros, but parts shipped with and for the quad-core Mac Pro are not forward-compatible with the 8-core Mac Pro.
This might cause problems for users who are considering an attempt at self-upgrading their quad-core Mac Pros to 8 cores when parts are available -- such a move would likely be warranty voiding due to the stated parts incompatibility.
It is not yet clear what distinguishes 8-core-compatible memory from the older quad-core-compatible memory though larger heat sinks are a possibility.
For the full list of compatible and incompatible components, see Knowledge Base article #305352.
System identification Apple has also posted a Knowledge Base article explaining how to identify the 8-core Mac Pro -- either by looking at the configuration label on the back of the system beneath the video ports for the string "3.0_8cx" or by going to the "About this Mac" window (under the Apple Menu), which will display "2 x 3 GHz Quad-Core Intel Xeon" on 8-core Mac Pros.
Feedback? Late-breakers@macfixit.com.Resources