It runs GTA 5 on max pretty fine, so I'm happy for the moment :P I did have a need for a fast CPU, RAM and a large SSD and was on a budget, so somewhere you have to make cuts :P
Oh, I didn't mean it reduced the VRAM *to* 200 MB, but *by* 200 MB. Was stuck around 2000 MB most of the time, but when looking at the hut it showed 1800ish. Sorry if that caused confusion :)
As far as VRAM goes, even if it would overrun and (as I understand) put stuff in the slower main RAM, it shouldn't reduce things to a complete crawl. Maybe some (stronger?) stutter, but not a grinding halt. At least, that's my understanding of things (I'm not an expert, just a humble web developer ;))
On a, well, related note: I did finally manage to find the problem after hours of tinkering around with inis, mods and looking up every damn google search I could remotely imagine. The VRAM was indeed a limiting factor, but not as you might think. Turns out it was a misconfiguration of the enblocal.ini.
I followed the STEP instructions for ENB which state:
VideoMemorySizeMb=<integer in MB, multiples of 1024>
;all 32-bit users and 64-bit users with less than 8GB system RAM, set to formula: [VRAM] + [System RAM] - [2048]
;64-bit users with >= 8GB system RAM, set to formula: [Total Available Video Memory] - [170 (for win7) or 350 (for win8/10)]
AutodetectVideoMemorySize=false
So guess I misunderstood the [Total Available Video Memory] part I guess and set 2048 for that. Resulting in me setting VideoMemorySizeMB to 1698. Yea... that happens when you try to use flu-induced sick days with clouded brains for some good Skyrim time :D
Thanks everyone for trying to help, though :) Definitely a cozy community here *starts setting up shop*.