Just got the legendary edition of Skyrim today and was wondering if there was a way to tell how much vram the mods you want will take up. I ask because I only have 1.25Gb so i want to choose the best mods i can that will work with that.
I use MSI afterburner to check VRAM usage. For skyrim, 1.25 Gb will be very tight. You won't really be able to use a lot of High Res texture mods or even bethesda's own HD texture packs. I have a 2GB GTX 770 and I still don't always have enough VRAM with High Res texture packs in certain locations. When I had my 1GB HD 6870's I was constantly running out of VRAM if I used texture mods.
If you avoid a lot of texture mods however, you should be just fine with that amount of VRAM. What GPU do you have?
High-res texture mods are going to drive your VRAM usage through the roof.
ENBs will use VRAM but are going to take a heavier toll on your processor.
Gameplay mods and such really shouldn't. affect you too much.
There's a Skyrim Performance Monitor tool that will tell you how much VRAM you're using.
In your case I would probably add on a less intensive ENB, but I'd be pretty hesitant to add a hi-res texture pack.
SMIM would probably be fine, though.