No. You can however use a single ATi card in an nForce4 motherboard, but not two in SLI. The ATi cards do not have the required connector to bridge the two cards together, nor do the drivers support SLI. There may be other, more fundamental reasons as well, but the aforementioned two are enough to know that ATi cards can not be used in SLI. If and when ATi comes out with a multi card/core alternative to SLI, I'm sure it won't be a secret.