Try Memtest 86+ Ver. 2.11 first.

If Test 0/1/2/3/4/6 didn't have any errors, that's not likely that your mem is the issue.
What I've found so far is sometimes tweaking NB DDR vRef will help stablizing Test 5 (less errors). Test 7 is more likely result in unstable FSB. FYI
After you pass all tests in Memtes 86+, try enter windows and do further testing so as to avoid system file corruption due to miscalculation of the machine