Liquid Cooling Experiments
In our recent review of the Thermaltake BigWater 760i, we complained about poor positions of liquid cooling systems in our local market. Indeed, compared to coolers for enthusiasts, this segment shows a deficit of market offers. Such coolers seem to be in demand, technical progress of liquid coolers accompanied by democratic average costs encourages users' interest. But nevertheless, retailers still ignore liquid coolers, even to a greater degree than at the time these systems only appeared.
The story of our experiments with liquid cooling of the GeForce 8800 GT will be quite illustrative in this respect. At first, we chose the Thermaltake TMG ND3—this product appealed to us with its configuration. Besides, it was available in the market, at least in Summer-Autumn. Well, we were still wet behind the ears! We addressed the marketing department of Thermaltake and asked to provide this liquid unit to carry out our tests. We received an unexpected reply: there had been none available for a long time already! They were ready to send the ND4, but the ND3 was not available! We are actually not a bunch of bloodsuckers, but we still tried to extort the product from a distributor. You may have already guessed that the distributor had none of them either!
OK, then! We addressed the nearest retailer in hopes to get the liquid cooler there, as it was included in the price lists a couple of weeks ago. Now imagine our surprise (and disappointment), when we found out that all devices had been already sold. Now that's a problem! What could we do?! We couldn't give up our interesting idea and put it on ice!
Of course, not! We decided to do it by hook or crook! We came up with a workaround! Our objective could be reached in devious ways counter to fatal circumstances. Fortunately, the alternate solution lied on the surface. Indeed, why get obsessed with the TMG ND3, if we could get the TMG AT3, officially designed for ATI graphics cards, but which was topologically compliant with NVIDIA solutions? So we risked to try this product!
The TMG AT3 is actually atypical of usual liquid coolers. It's a complex of elements, not just a liquid unit—it consists of a copper heat sink, a copper plate for memory chips, and an additional 70x70x15 fan for the working medium. That is, the AT3 replaces three typical components (a liquid unit for a GPU, a liquid unit for memory chips, and an additional fan) for a reasonable price tag for a liquid cooler. That's what we liked in the ND3—combined functionality.
The AT3 also offers good usability—it's equipped with a simple retention module with a sheet of heat-conducting gaskets (for memory chips) and a bundle for mini heat sinks for VRM elements. The bundle also includes fittings (for the inner diameter of 1/4" and 3/8"), a technical manual, and a grid bracket for the rear panel.
Fortunately, we were right to assume that the AT3 is compatible with the GeForce 8800 GT—the liquid unit fits almost as a native device, without cardinal modifications (we just had to make a small cut-out in the plastic housing for the fan header on the graphics card). The only problem is that the outermost memory chip is not covered with the copper plate—the layout of memory chips in ATI cards differs from that in NVIDIA products. This problem can be fixed by adding a special heat sink (judging by results, there is little difference between thermal conditions of memory chips under the plate and under a heat sink).
So, we've covered technical issues of the AT3 liquid unit. It's time to have a look at results of this product tested with the BigWater 760i!
Chart 9. VPU temperature readings.
Each cooler was tested with the stock thermal interface.
Chart 10. Video memory temperature.
Chart 11. VRM temperature.
Chart 12. Noise characteristics.
Background noise level: 18 dBA.
*VPU priority means that the GPU liquid unit is connected directly to the output of the radiator, the first element in the path; CPU priority means that the first element in the path is a CPU liquid unit. The Thermaltake BigWater 760i and the TMG AT3 are set to minimal speed in all tests (rotational speed of the on-board fan BigWater 760i is 800 rpm, the pump operates at 1200 rpm).
And now let's have a look at our charts.
Chart 13. Thermal resistance
Thermal resistance θja is defined as the relation
Chart 14. Noise characteristics
Background noise level: 18 dBA.
Chart 15. Efficiency/noise ratio.
The efficiency/noise ratio (ENR) is calculated as:
No need in any comments here, time to draw a bottom line.
Compared to the stock cooler of the GeForce 8800 GT, all third-party products look great! Even representatives of the "old school" (Arctic Cooling Accelero X1, Zalman VF700-Cu, and VF900-Cu LED) perform very well in our testbed and demonstrate much better results. To say nothing of the new products. Thermalright HR-03 Rev.A and Zerotherm Hurricane HC92 Cu 8800 prove that alternative cooling systems provide truly interesting technical characteristics for comfortable thermal conditions of your graphics card with minimum noise. Only these systems allow their users to overclock graphics cards to the highest level. We shouldn't forget about the Thermaltake BigWater 760i in tandem with the TMG AT3 (TMG ND3) liquid unit—this combination is practically the most efficient and good-looking cooling system for the GeForce 8800 GT/GTS. However, it belongs to a different class of products for another price segment.
Thermalright HR-03 Rev.A and Zerotherm Hurricane HC92 Cu 8800 get our Original Design award.
Our congratulations to the winners. We wish these companies new achievements in the field of feature-rich cooling systems. Let's hope that Thermalright and Zerotherm, as well as Arctic Cooling, Thermaltake and Zalman, will please users with more highly efficient and low-noise graphics card coolers. As for us, we'll keep tabs on this market segment.
Vitaly Crinitsin (firstname.lastname@example.org)
February 4, 2008
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