Hi Guys, ok. For all those who might want to try what I tried? Installing non ecc memory on a T40 to be used for development work? There is an error message issued when mixing ecc memory with non ecc memory. So you can't mix them on a T40 apparently.  I removed the 8GB ecc memory that came with the T40. I installed the non ecc memory and it worked fine. I also found out that it seems you have to install the memory modules in the slots in the same order as page 12 in the user manual. Don't quote me on that. But when I tried the memory was not recognized until I removed the 8GB and put the new memory modules in the 1 and 2 slots. I now have a 32GB machine running and we will take it to 64GB when we have the money next month. So I am very happy. I have a new Dell T40 working as it should and I am happy to be with Dell again. To all Dell employees who read this. Dell was GREAT in the late 90s and 00s and I was very sorry to have to buy competitive hardware. (In 2007 I tried to buy a new Dell Laptop and I was turned away. I wanted to buy Dell but Dell would not sell me the laptop I wanted. I bought my laptop from another vendor.) Hopefully I will use Dell for the years I have remaining in IT. If your marketing guys are looking for a great story? My story of why I only bought Dell for years is one of the better ones. I really hope my new little T40 is great and we buy more dell because "Dude, you're getting a Dell!" Best Regards Peter
Ok Guys, I am at the next step. I have 2 x 16GB memory modules as per this link. HyperX Fury Black 16GB DDR4 2666MHz CL16 Memory - PC Garage I have put one of them into my new Dell T40. I simply installed one of the 16 GB cards into the T40 memory slots. After reboot it is not visible to the OS or the BIOS. So I am wondering if there is something that I need to do to make the memory visible to the BIOS and OS? The guys at PC Garage said they were not sure if the 8GB installed ECC memory could be left in the machine when the 16GB non ecc memory modules were put in to the system as well. So now I am up to the stage where I am trying to find out if these memory modules can co-habit with the 8GB that comes with the system or if I need to take out the 8GB memory module and only have the 16GB memory modules. If you can share your opinion on this matter I would really appreciate your assistance. We bought the T40 from PC Garage but they don't know a lot about the details. Best Regards  Peter 
Installing HyperX Fury Black 16GB DDR4 2666MHz Into Dell T40