I dont know where you are going to get stock coolers But i have a whole writeup on modding 9800gtx's for watercooling. And from what ive found tri-sli 9800gtx's dont scale all that well. But fun stuff either way. take a look might help
http://www.overclock.net/water-cooli...save-some.html
http://www.overclock.net/water-cooli...save-some.html