|i had a dv6000 that was to meet basically the same fate, almost. the thing never really ran correctly, not going into standby and coming out of by itself, wifi not working sometimes, the stupid bios update that made the fan run full time, and the VGA out that had bad interference.|
um... try researching the specific models in the dv9000 series... find out another model with the desired GPU and find some good pics of it. maybe take yours apart and see exactly what the motherboard layout is like. then, go and try to find a replacement motherboard with for the model that has the GPU you want.
if the models are close enough, or at least in the same series, then the motherboards should be the same layout, and if so, you can swap them. only things i would watch out for are additional ports that you didnt have originally. these, if there are no holes on the case, will get in the way and you will have to mod the case to make the mobo fit.
btw $400 for another motherboard with the same design flaw is highway robbery. at that point, if not taking the above route, i'd sell the laptop for parts/repair on eBay and buy a new one, preferebly not from HP because they in my experiance are s---.
hope this helps