I was aware that you could upgrade the single cpu in a 4.1 5.1 using the Xeon W3680 or W3690 cpu. But I just read you can also use a core i7… "Single CPU Mac Pro 6-core upgrade: For the 4-core, single processor Mac Pro. Your stock 2.66 GHz (2009) or 2.80 GHz (2010) 4-core processor is upgraded to an Intel Core i7-980 3.33 GHz 'Gulftown' 6-core CPU. (The alternative 'Westmere' Xeon 6-core CPU provides identical performance but at twice the cost. It is not remotely cost effective). I use a Gulftown Core i7-980 in my 2009 single CPU Mac Pro". Has anyone done this? Does this mean there could be faster Core i7 upgrades available? I am aware that the ECC ability of the ram will not work.