Your ok. The Mem clock doesn't show the accual speed of the mem look here http://www.zotac.com/index.php?option=com_content&task=view&id=151&Itemid=283
If it regesters @ 1ghz it's accually 2ghz get it. my clock speed on my 8800gts (G92) is @ 972 mhz, but it's accual clock is 1970mhz. Download rivatuner and view your graphics card spec on it. you'll then will notice.