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There are also 5687's that are 3.6 quads I don’t know if they work in MP's though.

I have researched this. There was a member on this forum who tried it on a Single Processor Mac Pro and it did not work. I have googled it and can find no instance of the X5687 working on any Mac Pro. Further, I have researched the results ay Geekbench and can find no results of any Mac Pro using the X5687.

I did this, of course, because I in the market for the fastest 4 core CPUs that I could buy for my Dual Processor 5,1 and, I believe, the X5677 is it.

Lou
 
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