I've found memtest for windows much better than memtest86. I've also found that I can run memtest86 in the bios all day & night but when I run windows memtest or Prime95 I will get errors where I don't get them in the bios version of memtest86. I know it is the ram as I tested my cpu using low HTT and memory divider and it passed 12+ hours Prime custom test.
I ultimately use Prime95 as the final program in determining stability.
Michael