GTX 480 not working...?

SO I recently bought a more or less pre built computer (http://www.newegg.com/Product/Product.aspx?Item=N82E168...) it was $300 less than it is now  
I just got it after it was in seattle for 3 weeks with relatives, and I also bought a gtx 480 do go with it (http://www.newegg.com/Product/Product.aspx?Item=N82E168...) also about $20 less than it is now  

So when I unplugged the stock HD Radeon 7770, I tried to plug in the gtx 480 and when I attached my monitor (Hanns-G 269 27") it would just say "monitor unconnected" and stay in power saving mode.

I have tried downloading the drivers for the gtx 480 and updating the ones for the 7770 but 7770 is already at newest driver, and the installer says that there are no nvidia cards attached to mobo and will not download.

I tried taking out all video cards, but the integrated graphics (it said it had them...   ) were not "seen" by the monitor either.

I currently have a single six pin connector attached to the gtx 480, but there is also an eight pin connector right beside. Should I try to attach an eight pin connector there? I would try but my PSU does not seem to have come with any 8 pin connectors....