memtest86+ is good mostly to check RAM stability before loading Windows for the first time on fresh sticks. It will not guarantee any sort of stability in the Windows environment.
for that, you should follow Louissss's suggestion and use HCI memtest for Windows....much more sensitive to errors than memtest in DOS. I always find RAMs lose about 3-5mhz from DOS to Windows memtest.
another very, very quick and effective tool is S&M v1.7.6, available for download
at BenchmarkHQ.
turn CPU test to "disabled", set memory test to "loop", disable "safe mode", and loop tests 3 and 4 a couple times. S&M usually picks up errors in a few seconds that can take HCI memtest hours to catch, and are never caught by memtest86+ at all. example: I can run my sticks @ 3,4,3,8 275mhz ~500 passes of memtest86+ test #5 and 3 full runs of the whole test (many hours total time), and no errors come up. HCI memtest picks up errors at those settings after ~250% coverage (almost two hours). S&M starts registering errors after about TWO MINUTES of test #4.
S&M has saved me a LOT of time
