Copgun

Well once your VRAM caps from textures, the game will load the textures with your RAM, but only to 3.1gb before crashing. With your current video card I would say you're ok right now and you could load up more texture mods. I would use the Skyrim Performance Monitor to know your VRAM and RAM usage and avoid crashing/stutter.

It doesn't really have anything to do with your system specs after you've installed a good amount of high res textures, it's more based on the limitations of the game engine.

I would stick with 1k/medium res textures, they're still better then vanilla and will help keep you away from the 3.1gb memory limit.

Nvm. Try running BOSS and fo3edit. 99% of the time a CTD on startup means you have a plugin active that is missing a master that it needs.

I would download a new night sky mod

With any mods you're going to want to try and remove/add as few mods as possible on a save game or it could result in instability, I've never heard of someone removing then readding an official DLC but it probably left behind a lot of scripts and such. I would start a new game a see if the problem persists. Also use a save game cleaner tool and clean the dirty edits shown in your BOSS log with TES5edit.

I had a problem like this in certain areas, to fix it I let the skyrim.ini regenerate itself, basically move the skyrim.ini out of the skyrim folder in your documents. I believe the problem was caused by various quad core CPU tweaks.

Try clicking on the trees and using "MarkForDelete"

Download and run BOSS, read through the log and address any mod conflicts/incompatibilities. Download and run Tes5edit, clean any dirty edits shown in your BOSS log. Also you're correct with a new game, many mods often require a new game or it could result in major instability.

Update NMM

FWE adds custom weapons/clothing/meshes, what you're seeing could possibly be the error that displays when a mesh is missing. Make sure you've properly installed FWE and your game is invalidated.

It shouldn't be any less stable, as far as I know COT and ELFX change totally different things so long as you don't install the interiors option while installing COT. In fact I play with both and have no stability issues whatsoever.

Post your BOSS log

I see a problem with your load order, you have the MMM plugin for project beauty active, but you don't have project beauty.

So just start a new game?I would start a new game and play around on it for awhile to see if the crashing goes away.