There are no settings for adjusting RAM speed -- those settings exist on some high-end gaming and workstation-class systems.  That CPU runs the memory at 2666 MHz -- which is all your system can deliver as a result. CPU specs: [URL]  
I upgraded my RAM from 16GB 2666 to 32 GB 3200.  After the upgrade, I was shocked to discover the PC was still at 2666 RAM speed.  The best I can tell is that Dell does not allow the RAM to run at 3200 even when the RAM is capable. Is the RAM locked to 2666 speed max or is there a way to configure the PC to operate the RAM at 3200? Thanks!
Can I Bump RAM Speed from 2666 to 3200?