So, the other day I put in my friend's GTX 970 4gb (his isn't factory overclocked, the one I bought that comes tomorrow is and mine is a newer GTX 970 model)...
Right now I just have a GTX 660 2gb
And 100% of my crashes were gone.
Same exact load order, same exact mods (nearly 200 mods)...my FPS went WAY up to 60 fps (with ENB+parallax and a lot of intensive mods). I could zoom around the world SUPER fast...WITH NO SLOW DOWNS OR FREEZES. I ran super speed from solitude, to whiterun, to windhelm, to riften, to windhelm, to that mage city and finally to whiterun and ended back at Solitude. Even going near large battles with mods that add huge stormcloak vs imperial battles...no slow downs at all.
Not one crash, not one freeze and not one lock up.
And I did this for 3 hours.
I put back in my GTX 660 2gb card, as my friend didn't want to give me his
...and suddenly I'm crashing again within 5-15 minutes of game time.
So, if anyone crashes because of mods...most likely its not enough video ram and not a powerful enough card. Unless you have enough video ram already, but for me that was the only cause of my crashes. I have almost 200 mods, and my 660 crashes ALL the time on Skyrim to make it unplayable. With my friend's 4gb 970...not one slow down at all, not one crash, not one freeze for 3 hours and that is running super fast on high time scale.
I of course have ENB boost and SKSE memory patch. But those didn't solve the crashing for me. Also, when I was checking my GPU stats...forgot what program I used...but I noticed video ram spiked to maximum really quickly when playing Skyrim. It went to 2.5-3gb on my friend's 970, but no crashes or slow downs and never went past 3gb usage.
So 2gb is NOT enough for a heavily modded, high-end texture, ENB game