K i Just bought an ASUS EAH 4890 http://www.newegg.com/Product/Product.aspx?Item=N82E168... which I was under the impression is 2 x 6 pin. But there are 8 holes altogether on the card. My power supply has 2 x 6 pin and an extra 2 pin in that bundle of cables. But I'm not sure if I need to hook it up, it's going to be damn tricky. Does it matter what order I put the two six pins in I just put the one marked #1 closest to top and #2 next lol...sorry for being an idiot.
I take it the PSU came with a 6-to-8 pin converter (they are sometimes labelled as PCI-E 6+2)? If so you'll be fine, the extra pins are returns (earths) anyway.
There is no need to worry about which plug fits which socket, just connect either of your 6 pin connectors to the 6 pin and the other to the 8 pin with the converter.