Hello Desangla, this motherboard support 4 DIMMS of memory of 4 GB each stick.
You will be able to find more information on the following link. Also there is a list of tested memory. Intel� Desktop Board D5400XS — System memory
In order to find out if a memory DIMM is defective, I would recommend you to test every slot individually, inserting one stick of memory at the time. Make sure it reads 4 GB.
In addition, please make sure you have the latest BIOS version installed Download Center
