Quote:
Firstly during manufacter and in order to cut costs during the availability of components, Commodore produced various revisions of Amiga 1200 motherboards. Only revision 1D1 boards are suitable for this type of heavy expansion. Later 1D4 and 2B boards are known to have timing problems with regard to the onboard Gayle and Budgie chips. Revision 2B boards are somewhat more prone to these aforementioned incompatabilities. These faults can be fixed on these motherboard revisions with some careful work with a soldering iron, but it is easier to just use a 1D1 revision motherboard in the first place.
it seems your problems may be originating somewhere else.
Could it be heat issues? i know the 1260 runs cool but do you have other addons in the case if so you could require extra measures for cooling.
In what way is the system unstable?