After removing all the expansions, check obvious things like the CPU board is seated correctly and the power supply has stable +5V and +12V.
There is an issue with 22µF SMD electrolytic capacitors on the A3640 board which can cause the card to fail. Would be worth investigating further if you're using one of these.
Do a search on the A.org forums and you should find a big discussion we had a few months ago about this.
