Air cooling is something many enthusiasts are moving away from, especially with the latest Prescott CPUs from Intel. While you can still get decent cooling as well as overclocking results using air on AMD processors, the Prescott CPUs are simply too difficult to manage if you have any aspirations of overclocking them.

Water-cooling is another choice, but for some people, the budget and difficulty in setting up a liquid cooled system may not be worth their while. As for phase change, that may not even be an option as these kits are even harder to setup and as much as three times more expensive than water.

Heat pipes are the latest rage in air cooling the past two years, and we've seen such coolers perform with various degrees of success. The Zalman CNPS9500 LED Heatsink (provided by our buds at Crazy PC) we'll be looking at today features such technology, with a few extras that will appeal to both those who like "bling" as well as those who are noise conscious.

The Zalman CNPS9500 LED Heatsink

The familiar bloom effect we're used to seeing from Zalman coolers returns with the CNPS9500 LED. The CNPS9500 is no small cooler, and is one of the largest we've worked with recently measuring 85(L) x 112(W) x 125(H)mm. Thankfully, it does not have an enormous girth, so it should not interfere with components such as ram and provided the motherboard maker follows Intel and AMD specifications, most boards should be able to handle this cooler.

It will cause problems with some cases though, especially ones with fan ducts. As seen in the right image above, our Cooler Master Centurion 540 was not able to close the side cover with this cooler in place.

We didn't count them, but there are a large number of 0.2mm thick fins which equates to a large surface area for heat dissipation. The fins are arranged in an aerodynamically optimized tunnel design, which maximizes airflow contact from the fan. The entire package, save for the fan and mounting tools of course, is constructed entirely out of copper and weighs in at a hefty 530g. While heavy, it should not cause any problems due to weight.

The 92mm fan is of the LED variety and has a soft blue glow when powered on. As with many of Zalman's coolers, this fan is near silent at the lowest fan setting (1350 rpm/18dB). This is provided you use the included rheostat to control the fan speed. At high speed (2600 rpm/27.5dB), the Zalman CNPS9500 is quite audible, though still quieter than Intel's stock cooler under load.

Zalman uses a rather efficient heat pipe design, marketed as a "Figure 8". The cooler uses 3 pipes, but the inverted design creates a heat transfer capacity equivalent to 6 heat pipes. All these pipes connect to the base, which is machined very flat, though not to a mirror finish.

There are a few fan accessories included in the package, such as a rheostat, mounting tools and manual. Tools for installation in Intel P4 Socket 478/775 setups, as well as AMD A64 Socket 754/939/940 setups are included.

Installation is incredibly easy for Athlon 64 setups, as no motherboard removal is required. Simply remove the screws already present in the retention bracket, place the CNPS9500 on top and use the required clip to anchor it into place. Pentium LGA775 installation is more involved, and will require motherboard removal to install the support backplate.

Performance

MSI P4N Diamond: Intel P4 3.73 Extreme Edition, 2 x 512MB Corsair TWINX PC5400 Pro, ATI X850 PE, 160GB Seagate SATA 7200.7.

MSI K8N: AMD Athlon 64 4000+ (Socket-939), 2 x 512MB Corsair TWINX PC3200XL, ATI X850 PE, 160GB Seagate SATA 7200.7.

We'll be testing both AMD and Intel setups with near identical hardware save the CPU and motherboard. The Zalman CNPS9500 LED in the primary load results will be at high speed settings. Stock coolers from Intel and AMD were also thrown into the mix for comparison, as well as an asetek VapoChill Micro using the High-Speed fan, and a Koolance EXOS water cooling unit (in mode 3 - performance). Arctic Silver 5 was the thermal paste used for all the setups.

Prime95 was run for nine hours, with Folding @ Home running in the background everyday for four days to load the system and allow the thermal paste to even out. During the actual tests, we ran SiSoft Sandra's CPU Burn for 15 minutes, with Folding @ Home running in the background. Ambient room temperature was maintained at 23°C/74°F.

No surprises here with the Koolance finishing on top, but the EXOS was far noisier than the Zalman and asetek. Between the air coolers, the results were very close, but the asetek finishes ahead here. The Zalman was quieter though, and by quite a fair margin. It was clearly audible, but the asetek had a higher pitched whine, hence, more annoying in our opinion.

We did compare the Zalman and asetek at the quietest settings. One thing to keep in mind is that in asetek's case, you do need to replace the fan, whereas the Zalman just uses the rheostat.

	Zalman	asetek
AMD	51	50
Intel	56	56

We have a tie on the Intel platform and a small 1°C edge in asetek's favour on the AMD platform. Again, Zalman does get the nod when it comes to noise as the silent mode is barely audible with the case's side panel closed.

Final Words

Up until recently, I would have said there would be no way any air cooler would match the performance of the asetek VapoChill Micro, but today the Zalman CNPS9500 LED heatsink did so, and did so quietly. What is quite amazing is the Zalman manages this at very low noise levels.

At the lowest speeds, the Zalman is a mere 1°C warmer than the asetek cooler on the AMD platform, and matched the performance of the asetek on the Intel platform. As mentioned earlier, the low fan speed is actually quieter than the asetek low fan speed, so it's a reasonable tradeoff for noise versus performance.

Zalman's high speed is actually quieter than asetek's High-Speed and is 2°C warmer than the VapoChill Micro on the Intel platform and 1°C warmer on the AMD setup.

While the Koolance EXOS still holds on to top honours (it is a water cooling unit after all), the performance is not far removed from the Koolance, and the Zalman is far quieter than the Koolance's silent setting.

Installation was a snap for the Athlon 64, but some elbow grease is required for Intel installation. Another drawback, which is a problem shared by a large number of recent performance air coolers, is the size of the CNPS9500 LED heatsink will cause some issues in cases where there is a CPU fan duct present.

Noise was a non-issue with the cooler as the ATI Radeon X850 PE was easily the main source of noise in our setup. When we swapped the X850 PE with the XFX 6600 and closed the system back up, only when we moved in a foot away were we even aware the system was on while idling. High speed was definitely audible, but not really that annoying. As a performance cooler, the Zalman CNPS9500 LED heatsink is up to the task, but we feel its real strength is its ability to cool well silently.

Thanks to our sponsors at Crazy PC for making this review possible.

Pros: Excellent performance, very quiet, extremely easy to setup in Athlon 64 systems.

Cons: Intel installation is cumbersome, large size may cause installation issues with some cases.

Bottom Line: Overall, we found the Zalman CNPS9500 LED heatsink to be quite impressive, which isn't something we say very often about air coolers. The performance was very good, but when you consider the fact that our video card fan was the only noise source we noticed during testing, that says volumes about Zalman's dedication to silence.

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