Ok this probably is a stupid question, but...

...is there a way to change int res for 3d and 2d graphics separately ?

Being able to do so would come in handy for e.g. Persona 3. Native res for that
game is 640x447 (3d doesn't look too good at this res)...now if I change that
res to 1280x894 (2x native) the 3d graphics look really good, but I'll get GPU
limited in certain scenes. Using any res between native and 2x will solve that
problem (and 3d graphics still look good) but mess up the 2d graphics (like NPC
portraits, etc.) -so that's why am I asking.

Nope, no way. Texture filtering can be set to affect only (or mostly) 2D but if 2D are the usual static stuff, you can't handle them like textures which you can render them at different resolutions. The only stuff you can do with 2D graphics is filter them

Ahh, too bad (though I thought as much).

So it's either nice 3D, ugly 2D or ugly 3D, nice 2D for me. Damn.

Thanks for the info.