Got the 1230 Accelerator in the post today so just had to "test" it "quickly". A few hours later and many games and demos tested I now think I probably do need a stronger PSU. It runs fine with the A500 60W PSU for general things. It boots into Workbench and you can access CDs and launch games and demos. However there are the occassional random sudden system reset for no reason and I think this can only be a power issue.

So tomorrow I'm going to dig out my Goliath PSU and see if it is still working.