I'm surprised this isn't posted here already! https://www.reddit.com/r/skyrimmods/comments/6k58mf/dx9_4gb_memory_issue_should_be_fixed_in_new/ The new preview update in Windows contains an update that fixes this! Turns out the DX9 dev never even knew about it and when he found the issue on reddit, he pushed a fix ASAP! Instructions on how to attain the fix included.