|All OWC Upgrade kits for the Apple Mac Pro Quad Xeon are fully certified to the full Apple specification required of Mac Pro memory. These modules exceed JEDEC specifications and meet the more robust thermal specifications, including use of an Apple Qualified heat-spreader, as per Apple's specification.
Apple specifically designed the Mac Pro with more space between each slot to allows the use of a larger heat-spreader on each module. The larger heat-spreader and the use of the highest grade, thermally tolerant components ensures that these OWC modules you purchase for your Mac Pro Quad Xeon will provide a lifetime of reliable and trouble free operation.
Apple notes that using parts with the standard heat-spreader and which only meet JEDEC standard specifications can result in higher fan speeds due to increased internal temperatures and system controlled reduction of memory performance to prevent thermal overload. In our own testing, we have found that use of such modules leads to ECC errors and ultimate system lock ups as such modules reach significantly higher temperatures than those of Apple's qualified spec.
Two well known memory manufacturers originally listed their own JEDEC standard modules as being Mac Pro compatible. Within days of doing so, each removed this compatibility support after reports and testing which made clear JEDEC standard modules were not reliable in the Mac Pro. It is very disappointing that many other memory providers continue to list and misrepresent such modules as being correct for the Mac Pro.