I have been using 8gigs of 1333MHz Vengeance RAM in my system and I just noticed yesterday out of 8gigs,7.5gigs is usable. 514mb is hardware reserved. I went to regedit>memory management and checked the option 'clear pagefile'. Also I went to msconfig and checked if maximum usable memory was checked,as it was not. I changed the RAM slots with each other and also formatted my computer. After all this,it still shows 514mb hardware reserved. I don't know any other method of fixing this. My system was using 8gigs perfectly till 2 days ago. And I don't have even installed any new hardware also which may take that amount of ram. I know 514 mb is not that much,,but it may effect the gaming performance.