Mac Pro 3,1 GPU upgrade: Radeon HD 6970 drivers needed?

I have searched and searched and haven't found an answer (atlas that a non tech guy can understand).

So i have a 2 gig HD6970 that I have installed into my 3,1 Mac Pro and it won't work. I have it installed in the lower slot, the 8 pin and the 6 pin plugs on the side of the card are both pugged into the power sources were the old card was plugged into and the DVI cable connected to the monitor I have always used.

I understand that i won't get the apple boot screen, but when I turn the computer on with just the HD6970 installed it boots up, then you hear the fan kick on, then it shuts down again. It keeps doing this for as long as I will let it.

Do I need to download drivers for this card before I installed it (obviously before)? If so, where do I find these drivers and when I open them on the computer will they automatically install, or do I have to do some techsavey stuff and plug them in some obscure area within the depths of my mac pro?

I know this subject has been beat down in the past, and many have claimed that this card isn't compatible but there are more than a few who have it installed and working.

Thanks for the help!

James