This usually means a driver has corrupted the Memory Manager's page frame list. ntoskrnl.exe is likely NOT the culprit but it is the one that triggers the BSOD once it detects that somebody corrupted its lists. I also highly doubt that you've turned off all 3rd party drivers, since there's no real straightforward way to do this without doing it manually by modifying the registry or doing some advanced Device Manager stuff. If your RAM is fine, it's most likely a 3rd party driver causing the corruption. If it was a major MS driver doing it, we'd all likely be having issues with it which we obviously aren't (and it would be caught by MS QA labs pretty fast too).
EDIT: If you upload your minidump somewhere, I can analyze it in WinDbg.