This the card? Nvidia Geforce 9600+ 1GB HDMI Graphics Card : Nvidia PCI Express : Maplin
If so it doesn't have or need an external power connector. Here is a blow up of the card,
If it needed the extra power connector it would be in the blue square, and is quite clearly missing, so no issue there. I assume the 2 pin connector that you are referring too is the one circled in red. If so that is a SPDIF header and you connect a 2 pin SPDIF cable from that to the one on a sound card, and then you can pass audio over the HDMI connection.
As for the problem with the card it is quite possible that it is a dud out of the box. Not unheard of for that sort of thing happening, and not fun when it happens to you.
Another thing about that card, not sure exactly what it is. It may say 9600+ on the box but in going to Inno3D's website I can't find it. Even more confusing about it is the listed specs, if those are correct then I don't know what that card is supposed to be. There is a "green" version of the 9600 GT, Inno3D Unveils Green 9600GT E-Save, GTS 250
One person in the Maplin comments said that it is actually a 9600 GSO, but even then the specs don't match up, Video Card Comparison - GPUReview.com
with either of the two GSO versions.
All things considering it does sound like a dud card, and you would probably be better served returning it for another.