Hi people, Well after reading about it and finding myself a W3680 hex core 3.33ghz boxed retail (DAM HARD TO FIND A RETAIL BOXED) I did the upgrade on my mac pro 4.1 2.66ghz quad. All info can be found in the following link on how ECT. also all the do's and dont's. make sure you read all the thread as some have made a few mistakes like flashing macpro 5.1 to 4.1 and it not working! netkas.org http://forum.netkas.org/index.php/topic,852.0.html I now have me a 3.33ghz hex with 12g of 1333mhz speed ram from crucial and it was all completed inside 20 mins. my 4.1 2009 machine was a late one with the 08 efi so updated to 5.1 03 efi without a hitch, removed CPU board, removed heatsink which revealed a 2.66ghz Nlem quad with IHS so removed cpu, installed W3680 cleaned surface of cpu and heatsink with alcohol, AS5 applied, put heatsink back on, installed the 1333mhz DDR3 and replaced CPU board. P-RAM reset on first boot. and hey presto! 3.33ghz hex and 1333mhz DDR3 CPU temp 26c ambient temp 20c and thats after an hours running, AS5 can take upto 200 hours to cure and settle so i might see a few C lower yet but iam very pleased with that. Now the good bit! CPU cost £500.00 Ram cost £110.00 now i should get some return on 12g of the crucial 1066mhz ram and also the Nlem 2.66ghz quad. If i can get £200 for both that makes me a 3.33ghz hex 12G 1333mhz for £410.00 and a nice upgrade for my Mac pro. Thanks go to MacEfirom for the utility and to netkas for a great site to view, read and learn from.