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MillimeterLiquid-cooled HP Z800 Workstation Test Drive
Aug 10, 2009 12:00 PM, By Jan Ozer
Figure 3. Waveform for air-cooled system shown with 500 percent vertical zoom.
Testing
To test the noise characteristics, I configured the two Z800s almost identically, with Intel Hyper-threading Technology (HTT), Intel Turbo Boost, and Enhanced Intel Turbo Boost Technology all enabled. Note the slight differences in the configurations of the two systems: The liquid-cooled system was running Intel’s new 3.33GHz Nehalem Xeons with 24GB of RAM, while the air-cooled system was running at 3.2GHz with 18GB of RAM. Both systems were configured with 64-bit Windows Vista.
I installed Adobe Creative Suite 4 (CS4) on both systems and, one at a time, started encoding a ballet project that consumed 100 percent of all available CPUs in the past. Then I hung a Shure SM57 microphone behind the system being tested to record 10 seconds of audio in Adobe Audition.
Then, in Audition, I grabbed a 10-second section of both recordings and used the Zoom-in Vertically tool to zoom in by 500 percent. The waveform for the air-cooled system— again, at 500 percent vertical zoom—is shown in Figure 3.
Figure 4. Waveform for liquid-cooled system shown with 500 percent vertical zoom.
Figure 4 shows the waveform for the liquid-cooled system.
The waveforms obviously illustrate a significant difference in both volume and regularity. Lower volume is always good, and in a recording scenario, regularity makes noise much easier to remove via the noise-reduction modules found in most audio editing programs.
Beyond the waveforms, you can listen to the two recordings, though you’ll likely need headphones to really isolate the difference between the two. (Listen to the liquid-cooled system and the air-cooled system. Note that I boosted both recordings by 20dB to make them more easily audible.) In addition to volume, you’ll notice that the air-cooled system had a whinier, dentist-drill sound with lots of irregular noise as reflected in the waveform. In contrast, the liquid-cooled system was much more regular and lower-pitched.
One final point: Though the liquid-cooled system ran at a higher clock speed, which theoretically should generate more heat, it also ran slightly cooler than the air-cooled system as measured by Real Temp 3.0, a utility from Kevin Glynn. The difference wasn’t significant—about 1 degree Celsius cooler on all measured cores, but it’s nice to know that the liquid-cooling system delivered equal or better cooling than the noisier air-based system, since excessive heat can shorten processor life.
Continue the discussion on “Crosstalk” the Millimeter Forum.