On Tue, Sep 09, 2014 at 07:47:21AM -0400, Bob Metelsky wrote: > actually this is a dell 9100 (desktop) According to this: ftp://ftp.dell.com/Manuals/all-products/esuprt_desktop/esuprt_dimension_desktops/dimension-9100_owner%27s%20manual_en-us.pdf ...under "Specifications": Maximum memory: 4GB. The el6 x86_64 kernel is capable of addressing 3TB (with a theoretical limit of 64TB) of RAM, according to this chart: https://access.redhat.com/articles/rhel-limits So, the limit is in your hardware, not the kernel you're using. -- Jonathan Billings <billings at negate.org>