AFAIK the Amiga system has memory priorities. You can configure (or perhaps the drivers configure) priority. Putting accelerator fast memory over motherboard fast memory.
Are you sure about this?
I was told that the cyberstorm logic assigned the burst mode ram on the cyberstorm before the memory on the mainboard.
But I guess the memory timing/cycles for the cpu (040/060) would bee slower if you have simms in the mainboard.
I'm sure someone correct me, if this is total bull...