Put two of these in a cheesegrater macpro 2010-2012 and you have maximised its possible cpu performance , could possibly run at 4 GHz or slightly higher if it were possible to hardware mod the frequencies on a macro beyond that set for the chip my 5650 in a pc runs at 4ghz no issue. But 12 cores at 3.46 is a big improvement.
2 x Lidded X5690 6 core 3.46GHz to upgrade a Mac Pro
The, `easy to install`, comment is quite correct if you did what I did and de-lidded each CPU because these chips had to fit into an early 2009 Mac Pro. I would guess that the de-lidding and the careful cleaning of the CPU`s took about 2 hours to prepare them for installation. The actual installation procedure took just over 15 minutes. If you were going to install these CPU`s in a genuine 2010 Mac Pro you would, after some cleaning up work, simply just exchange the existing lidded processors for the supplied matching pair. The whole system is now working very quietly and as you can imagine, very much more powerfully. Thank you Kelsus. A good price for two VERY good and stable CPU`s.