If you're absolutely sure it's not related to load order or compatibility between mods, you may be hitting your VRAM's limit. There, you'll start seeing floating grass in the wilderness, interior spaces and generally in places where it shouldn't be. Shortly after, the game will either freeze, or outright quit.
If your game is heavy on texture replacements/mods, this is where ENB comes in. It cooperates quite nicely with Sheson's/SKSE's memory tweaks. If you don't want to use the graphics enhancement part, open enblocal.ini, find UsePatchSpeedhackWithoutGraphics=false, change it to true and save it.
Now: Because Skyrim doesn't really like getting pushed beyond it's limits, you may still get the odd silent crash, every 4-6 (maybe even more) hours of gameplay.
Hope it helps