The memory will perform optimally with a single 16 or two 16s, or two 8G modules. Mismatched modules will run at least in part at half-bandwidth.  
According to Dell's specs, my Inspiron 7580 laptop cannot support greater than a 512g internal SSD or 24g RAM (only upgrades possible are 2x8, 1x16, 2x16, 1x32 and 2x32). I currently have a 256G SSD and 8G RAM. Upgrading to a 1TSSD and adding a 16G RAM chip are the most logical upgrades but Dell says not possible. Anyone know what is real? Crucial recommends several Tb SSDs on their website for my 7580 and another discussion here says a different Inspiron laptop can support 24G RAM but only the 16G chip is in the fastest mode. The 8G is chip is used but with slower access. Crucial hasn't responded to my email questions in a week and other customer support sites, including Dell, just read the specs to me out loud. Dell only has 512G SSDs for sale for my machine which suggests the 512 limit is real. I bought the darn laptop expecting to upgrade RAM and memory but wasn't told of the limitations.  Thanks in advance for help.
spec limits real inspiron 7580 laptop?