It sounds like Asus ran out of fans, then grabbed one from the olde mystery box. Kept around for emergencies like this. If the fan is indeed an underpowered wonder, this is an example of OEM vendor honesty at its best. Not. There seems to be an unspoken current of fear running riot through the PC industry. Grab that money and push the hard or software out the door, for there may be no tomorrow! Ship it, ship it, ship it! If it doesn't work, who gives a rat's posterior?
You can squawk to Asus or the r/etailer you bought this Vidcard from. If you want to use the 7700 soon, it may be quicker to look at the HS carefully. Nice big n' fat fans can be substituted in place of weenie one's. This may involve having to slide(from underneath one of the two white plastic pegs that hold the GPU's HS on the Vidcard) the red and black wires that lead from the fan to the tiny plug that fits into its opposite member of the plug on the Vidcard.
If you decide to avoid disturbing the white plastic peg(you're up the creek if you lose one)you'll probably have to cut the red n' black wire to get it off the Vidcard and out of the way. This voids your warranty, btw.
After five months of perfect operation of my Elsa GF 256, I threw caution to the wind and clipped the red and black wires, making it possible to slide 'em from underneath the white plastic pin without disturbing it. Having the GPU fan running from the Vidcard is a stupid arrangement--especially with the King Kong of power leaches, the original GF's. The weenie Aavid stock 40mm fan was replaced with the thickest 40mm I've ever seen. ~9 cfm as opposed to ? 3 cfm from the Aavid.
It's up to you. Best of luck!