no signal on monitor and then boom

hi guys. just did a home build

asus k8vse mobo
2x512mb kingston cl2.5 ddr dimm
amd 64 3200+
asus v9999 geforce 6800
400w psu

ok and here comes the problem.
i powered on the new build pc and there was no signal to the monitor. I checked the monitor on another pc and had no problems. i then tried this graphics card on the other pc which has integrated graphics anyway. the card installed no probs and ran fine.

this card says its agp x8 x4 and x2. it also takes 2 molex off separate power lines. both mother boards are agp x4 and agp x8 standard.

Now my new mobo will not accept 3.3v agp x1 x2.

on with the story.... i tried another agp x8 card in to my new mobo which did not need a molex connection. it worked fine.....on replacing this old card and putting my new asus v9999 in to my new mobo and powering up i got a loud beep and the computer shut down...like a fuse had blown or something..... took the card out...no visible damage...placed older card back in and all is fine...tried this asus card in my older pc again..it booted up and all of a sudden there was smoke everywhere (arrrrrrgh). now im pretty sure that something has blown on this card.....

my main question is, bearing in mind that i used esd protection on install and ive done plenty and i checked all power connections etc.. was the card likely to be faulty or did i make a very expensive boo boo....any help or ideas would be appreciated as im sending the card back for inspection and id like a better idea before getting fobbed off.

cheers P