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Here is what Dell has to say about upgrading ram in the 560/570 series "Connectors four internally-accessible DDR3 DIMM sockets
Memory-module capacities 1 GB and 2 GB
Memory type 1066-MHz DDR3 DIMM;
non-ECC memory only
Memory configurations possible 1 GB, 2 GB, 3 GB, 4 GB, 5 GB, 6 GB, 7 GB,
and 8 GB
NOTE: Memory configurations of more than 4 GB
require a 64-bit operating system."
That info was found in this PDF http://support.dell.com/support/edocs/systems/insp560mt...
To summarize: 8GB max at 1066MHz which is interesting since you're sporting 1333 ram... hmmmm
Hope it helps