After too many odd crashes I learned to never mix memory types. At office, shop and home we install all the same sticks or don't do it. While you are free to try this, no shop or tech I know will say it's OK.
Have 2100 and 2700 DIMMS now, with one bank now defective. Can I use PC 2700 DDR CL 2.5 DIMMS in this machine? These are Kensington KVR333X64C 25K2/2G (2 GIG) chips. Will replace all the old chips, with 2 GB total. Using Linux Mint MATE 17.1 on one drive and Windows (seldom) on the other, boot drive (MBR instructions for Linux boot, default.