@Amigamia
I dont recall AROS ever having a 1GB RAM limit.
It supports 3GB RAM for 32bit version, and that's not including VRAM.
My AROS box is an i7-4790k overclocked to 4.58ghz with 4GB of ddr3@2250mhz (2x2133mhz modules, but the oveclock on cpu also overclocks the ram) and a 1GB gtx275 and I end up with 3GB of usable system RAM. This doesnt change even when swapping to a 512MB card, so it suggests the system is limited to 3GB RAM and that I dont just lose a full GB because of VRAM.