Reading through the reviews it seems to me that Qmax is the maximum wattage of heat to power dissipation.. TDP is the maximum power to heat that the CPU will disperse.. This is only my reasoning (correct me if I am wrong).
If the Qmax of the heatsink/fan is rated to 350w, it will cool the CPU running at maximum TDP (ie 125w) in a proprtional ratio and cool it well. If your qmax is close or lower to the TDP of the CPU then the cooler won't work or won't work well for that CPU. Remeber due to the green brigade CPU manufacturers are trying to get the TDP of any CPU as low as they can without affecting performance.
I have read on some suppliers sites (recent) that the Zalman CNPS9900 will cool AM3+'s as well, bearing in mind its Qmax is 350w and AM3+ TDP's are generally in the 95w range and below (again correct me if I am wrong).
Me personally am not a fan of Zalman heatsinks. They tended to concentrate on noise reduction at the expense of reasonable cooling, but they do look nice. If I am not overclocking, the stock heatsink does fine, I have tested this many a time using Handbrake to convert DVD formats. This uses all the cores on any CPU to the max and will cause a system to crash if the CPU cooling isn't up to it. On my Q6600 the temps overclocked on stock heatsink running at 3Ghz went up to near 70 deg C with no problems. I replaced the stock with an ARTIC freezer Extreme heatsink and got a 20 deg C reduction in temps.
I have been programming on computers since the ZX81.
I am an apprentice trained Electronics Engineer with qualifications to back it up.
I have been repairing computers since 1996.
Yet to some people I still know nothing...