CNPS9900 comes in several flavors; there is the -LED, the NT, and the max (-r or -b is just color of led).
The -led is inbetween the 9700 and the 9900max in terms of performance . The Max competes with the top end of coolers cost is about 80 bucks (got it on sale for $65).
Would expect closer to 5C above the temperature inside the case, which should be a couple of degrees above room temp.
As I indicated, idle is not that important, it is how hat does it get under load, either durning gaming, or prime 95 (MAX load)
Comparision chart
http://www.guru3d.com/article/zalman-cnps-9900-led-review/6
Quote from last page of link
Make no mistake though, the cooling performance is grand and if you stick to 40% to 60% fan rotation, it's not at all noisy. We achieved a 3600 MHz overclock on a 1600 MHz FSB based processor, while retaining fairly good temperatures. And that QX9970 is a hot processor all by itself.
Next to that the design is very pleasing to the eyes and it's definitely a quality product, and as such it comes recommended as it'll do a fine job cooling wise, and well .. it just looks stunning. End quote.