Have you bought just another 1gb ram stick? Or replaced the 1gb with a 2gb.
Did you check the speed of the ram that was in there and what speed your Mobo is compatible with?
I5 3570k oc'd 4.3Ghz, CM hyper 212+cooler, Gskill 8gb 1600Mhz, Gigabyte 7970hd oc edition, msi z77a-g45. Samsung 830 256gb SSD, WD cavier black Hdds