@aravind_n20
you will be sorry to learn that another pair of 512 Mb will not give u any performance boost, infact, it will drop the performance, u got A8N-E, as i see, u can hope to run them at 400Mhz if u get the same exact ram with same timings, and preferably same factory, otherwise, ur timings will drop, and so will the performance, if u wanna put in 2 Gb, sell this sticks and get 2x1Gb sticks to run in dual channel.