Hey Techknight thanks for getting back to me. The plot thickens, but I can rule out the cards as the issue, as the stock card is triggering the bus error now on boot as well.
Though taking your advice, and setting up the cards for 5MB, it seems to work fine now, no boot problems and no flickering with that one working card in the 5 MB configuration, but the other card that didn’t work in my fist post when configured for 5 MB won’t boot at all (just chime and nothing no bus error either)
With all the examples in my previous post, the jumpers were set at the 7MB on position