2008 R2 is 64-bit only, as such can definitely use more than 4GB ... Standard does have a max of 32GB. I would first check BIOS to make sure that memory "mirroring" is not on.  Several 410's shipped with mirroring enabled by default from Dell.
Hi, we just installed a new Poweredge R415 that had Windows 2008 R2 x64 (Standard Ed) installed and it's only seeing 4GB of RAM of the 8GB we had installed (it reports 8GB installed; 3.99gb usable). From all of my reading the standard edition of 2008 should be able to see up to 32GB of RAM.   Did I blow it with the OS I chose at purchase or is something really weird? All I've done basically is turned on the system and been checking to make sure it runs ok. I'm a bit baffled by this one since it IS a 64-bit OS and reports as such. Thanks for any help!
Poweredge R415 / Windows 2008 R2 X64 only sees 3.99GB RAM?