First of all you do have a 64 bit maya installed right?
if not download it here;
https://usa.autodesk.com/adsk/servlet...linkID=9242259

if you have a dual quad core then that changes things;
-set the amount of rendering threads to 8 since you have 8 cores
--set memory limit to 0 making it Unlimited if i remember correctly

try loading or rendering a really heavy scene and watch if it works okay