Hi, I have a 4,1 Mac Pro (2009 model). I recently ordered 64 GB of OWC RAM (4X16GB). The RAM arrived on friday, so i decided to run the Apple Service Diagnostics (ASD version: 3S132) on the RAM to see if everything was ok. It passed all the tests, with the exception of the SMBIOS tests. These are the error messages : Now my thinking was the error messages popped up because the 2009 Mac Pro was never officially supported by apple to accept 16GB DIMMs, and when the SMBIOS runs the self check it just can't reconcile the large size of the DIMM. I called up OWC and shared my thoughts with their tech support. My agent said he never heard of that problem, after i told him my hypothesis he spoke to another agent and said his colleague agrees with my thinking. I just find it strange that all my google searches turn up nothing on this scenario. I would think it would be a common occurrence with everyone who has upgraded their RAM past spec. The one actual google search result that i did find was on the apple forums, and the consensus was the RAM was bad. https://discussions.apple.com/thread/2738395?start=0&tstart=0 So i'm not sure if my hypothesis is correct, or if OWC tech support was just placating me. I should mention that i haven't experienced any trouble with the system so far, and that i just have the 4 16GB DIMMs (no matching with other sticks). Anyone here have any 16GB DIMMs in their Mac Pros? Ever get that SMBIOS error?