DDR3 1600 RAM; What to Buy?
I'd either go with Crucial. See a 2x4GB set for the XPS 8500 here:
Or, if you wanted 24GB total (existing 2x4GB set that shipped with it + a 2x8GB set), add a 2x8GB set to what you already have:
But, if you go with other memory, make sure to get memory others have found works OK. One thing you'll notice if you read through customer reviews, is that some memory wont' work at 1600Mhz with the XPS 8500 if the timing is too aggressive
See reviews of desktop memory at newegg, searching for reviews with XPS 8500 in them:
Note that a number of XPS 8500 owners have reported that memory that used more aggressive timing would not run at 1600Mhz; and CL11 seems to be a better bet (as in some of the Kingston memory others reported works fine in that desktop model).