Lower clocked ram "should" work and the performance difference wouldn't likely be noticeable. That said your best bet is to contact Asus with the exact ram specs as there a lot more than speed and size to consider with ram. Timing, latency, all make a big difference as to whether it will work or not.
And I must ask, what in the world do you need 32gb of ram on a laptop for? If you're gaming and hoping it will improve things, it won't.