hmm . They should . what slot did you put it in ? The # 1 slot is the farthest from the processor , with the white tabs , the # 2 slot is the next white tabbed one , closer to the CPU socket , the # 3 slot is the black tabs farthest from the CPU , and the # 4 slot is the black tabs right next to the CPU . Now that I am at my computer , I am going to list every single stick I have here , that I know works , since I have quite a array of 2 gb , 4 gb , and 8 gb sticks that I have upgraded through . In the DSmedia server the sticks are as follows 2 x 8192 MBytes Hyundai Electronics PC 314200 889 MHz HMT 41 GU 7 AFR 8 CRD and 2 x 8192 MBytes Hyundai Electronics PC 312800 800 MHz HMT 41 GU 7 AFR 8 CPB For a total of 32 gb . This works in all my R 210 ' s and R 210 ii ' s . Does not work in R 310 ' sthey are more pickey than the R 210 ' s and R 210 iis areIn the PFsense R 210 ii 1 x 4096 MBytes Samsung PC 310700 667 MHz M 391 B 5273 CH 0 CH 9 1 x 4096 MBytes Hyundai Electronics PC 312800 800 MHz HMT 451 U 7 BFR 8 APB Makes 8 gb in the PFsense box . Hardly use half of it with PFblocker , squid , squidguard , ect running . I even have an SSD as a boot drive , and var and tmp as RAMdisks to halt as many writes on the SSD , each has their own 994 MiB RAMdisk , and RAM usage is still just under 4 gb most of the time . Spares 2048 MB Hynixsame as hyundai electronics , fyiHMT 125 U 7 TFR 8 CH 9 Edit cannot seem to find my 4 or 6 other spare 2 gb sticks , but I will post them when I get them . Most of these are 2 rx 8 . I have two 1 rx 8 2 gb sticks that did not work in my R 210 or R 210 iibut they did work in my R 310 .