first off I don't have them and never tested them. i purchased 4gb sticks from the same seller. code for 5 bucks off is = Bat5 after reading the links below I think the ram above would work in the smaller 2010 mac pros using the 1066 speed sticks. price is good 227 an 8gb stick http://download.intel.com/technology/memory/DDR3_RDIMM_UDIMM-ECC_NHM-EP_validation_results.pdf http://download.gigabyte.eu/FileList/QVL/networking_qvl_v1.0_ga-7tcsv2_v1.0_092809.pdf http://www.samsung.com/global/syste...family/2010/1/1/ddr3_product_guide_oct_09.pdf I won't be able to test these as i tested the 4gb sticks about a week ago. sorry for confusion this all applies to 1066 sticks the 2.8 quad core and the 3.2 quad core from 2010. I put in 1333 by mistake.