Those are the specs, but not the model, but there isn't anything obvious about the specs that they shouldn't work. "says that ECC is now disabled because the configuration isn't right (they are not pairs)" What is the EXACT message it gives? Either way (and you can probably just skip the above): Populating A2/A3, B2/B3 is for "Advanced ECC", and you may need special DIMM's for that.  Advanced ECC is a feature that is NOT necessary for MOST computing needs, especially if you are using it at home. Put your 4GB DIMM's in slots A1/A2, B1/B2, and change the memory mode to Optimizer in the BIOS.
My work recently let me have one of their old servers, an R710. It had only 4GB of RAM in it, configured as 4 x 1GB DIMMs installed in A2,A3,B2,B3. Since I wanted to use it for virtualization I decided to upgrade the memory and have bought 4 x 4GB DIMMs (total 16GB).  All the old memory is DDR3 - 8500E The new memory is DDR3 - 8500R When I plugged the new DIMMs into the same slots it detects as 16GB but says that ECC is now disabled because the configuration isn't right (they are not pairs). I have tried putting them in all sorts of different ways in A2/A3/B2/B3 but it just won't configure correctly. The worst part is when I put the old memory back in that then has the same error where it didn't before. Initially I thought the memory I had bought might be wrong and that still may be true (it did specifically say ECC for an R710), but I have this nagging feeling I am doing something stupid. Any help / feedback would be much appreciated. Regards Nokem
ECC DIMM Configuration Question