I was wondering the same exact thing as you. I just picked up the Zalman 9700 LED( not sure if you meant the 9700 NT) from Fry's earlier today. I also noted that I seen the 9900 LED too, was wondering since this one did not say AM3 on it like the 9900 if the performance would be sub-par compared to the 9900; however, looking at the reviews the 9900 scored lower then what the 9700 did when it came out. So my question is is the 9700 better for my processor or should I get the 9900. Which processor did you use it on and how are you liking the 9700 ? I am currently working with an AMD Phenom II x6 1090T 3.2GHZ.
it seems the 9900 performs a bit worse than the old 9700. so looks like i'll be getting the 9700 from the results of that review.
I think the CNSPS9900 performs better but bear in mind it does have a correct orientation. If installed upsidedown it is worse than the older 9700. The 9900 has a bigger side with two heat pipes and slimmer side with one heat pipe. The bigger side is supposed to be positioned upwards or towards the exhaust.