Hi Chris, Just to close out this post. My T40 is running fine with two of these memory modules in it.HyperX Fury Black 16GB DDR4 2666MHz CL16 Memory - PC GarageThe trick was that I had to install them in the 1 and 2 slots according to the manual. Not just in the first two slots physically in the machine.I intend to buy two more at the beginning of next month when I get paid.Best Regards Peter 
Hi All,I know that the memory we put into a DELL T40 should be ECC.But we want 64GB in the new server we bought and I would like to know if non ECC memory will actually work.I am guessing it will work unless the BIOS has some check for ECC and rejects non ECC memory.Could anyone here confirm that non ECC memory will work before I open the packaging on one of the memory modules and test it?Thanks.Peter
Does the T40 accept non ecc memory?