Okay I purchased 3 sticks of ram today for 302 bucks. 12 gb total ecc. they arrive next week. I will get back with test results. the last purchase of 12gb ram needed to be returned wrong ram. this is a different seller i will let you all know how it works when I get it. It is listed as APPLE MAC PRO ram. I don't want to say any more until it arrives. as an aside I am doing some testing on this card from owc. Comes with a cd driver that must be used and does not boot mac.. BUT it is giving me raid0 transfer speed of a 700gb clone at 210MB/s. I have a 4.5tb software raid0 in the mac pro with 3 wd 1.5tb caviar blacks. and a 4tb raid0 of samsung 1tb f3's in a owc QX2 esata cable is the link. http://eshop.macsales.com/item/Newer Technology/MXPCIE6GRS/ as a note you can use the qx2 as a boot drive with fw800 or usb2 cables. just keep only 1 cable attached to the mac.