My A2000 came with one of these which I've been trying to get working recently, but it isn't 100% reliable and often crashes on startup. I've also tried it in an A4000, where I get the same behaviour. At first I thought it was a cooling problem as the 486 didn't have a fan or heatsink, but this appears not to be the case.
If this one does start reliably then I am interested in it. It also has more RAM than mine, and the coprocessors.
Could you tell me what the video card is, and whether you have drivers?
Thanks,
John