NZXT Kraken G10 Graphics Adapter

Cooling | Graphics Cards
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FAN & PUMP SPEED CONTROL

Untouched in all of the previous discussion is the question of how the fans and pump in a G10 + AIO water cooler system would be controlled. During the testing, everything was set manually, for the sake of complete control. This is not how the typical end user would want to control the cooling of their video card. Stock video card coolers have fans that are thermally controlled by a chip on the card, with some user control of the fan curve via provided utilities. All stock VGA cooler fans ramp up to a plainly audible speed when pushed hard; many are downright noisy. The 28 [email protected] maximum SPL of the ASUS GeForce GTX 680 DirectCU II OC is one of the lowest for stock VGA coolers; it is still a level SPCR would not consider acceptable for any significant length of time.

There is no easy way for the G10 + AIO cooler fan(s) and pump to use the fan controller in the video cards, so the options are motherboard fan header controls, and/or whatever software is provided with the AIO water cooler. There is probably no way to use the GPU thermal sensor as a control reference for G10 + AIO water cooler pump/fan control. Most current motherboards have fairly sophisticated fan control utilities in the BIOS, and even more sophisticated utilities for Windows. It's still possible that some canny combination of motherboard fan head controls and the fan/pump control utilities provided by the AIO cooler maker will work to provide dynamic fan and pump management that is both very quiet and very cool. Whatever options you choose, it can get complex, and you'd be well-advised to think through the cooling/noise for the whole system, and experiment to make sure things work as you intend.

One viable option with an AIO as capable as the Kraken X41 is to set up a fixed speed fan/pump system that provides safe temperatures under high load... and simply turn the pump off when not gaming or doing any high GPU-demand activities. I tried this with the Kraken X41 on our ~200W GPU. When the pump was switched off while the system was at 17 [email protected], with just the fans on, the noise level dropped to a very smooth 14~15 [email protected], quiet enough to be perfectly acceptable even to me. With the pump kept off for about an hour, GPU temperature remained mostly under 50°C with modest Windows activities like web surfing and HD video play. Yes, even with the pump turned off, there is cooling, via water conduction, and from the 92mm fan on the G10 bracket. With modern GPUs that draw little power until 3D processing is demanded, this seems a perfectly viable option. The audio amplitude reduction with the pump off is small but quite perceptible because of the sound quality difference (as you will have heard in the MP3 recording on the previous page). In any case, most gamers hardly notice a little more noise during intense gaming, especially over the sound effects.

FINAL THOUGHTS

Getting back to the actual product under review, the NZXT Kraken G10 does provide excellent cooling with surprisingly low noise (but not without some effort) when combined with a high performance AIO CPU cooler. Despite reservations about the quality of the fittings, mismanufactured parts, and the sturdiness of the bracket itself, the G10 worked as intended. Perhaps at just $30 and with such broad compatibility, we cannot expect flawless precision.

Keep in mind that our test involved only one 200W video card, and although the latest nVidia GTX 980 and 970 GPUs are rated for just 165W TDP, single GPU cards approaching 300W peak still abound. We cannot comment on how well a G10 + AIO water cooler would work with such hot GPUs, nor the effect on cards where the VRMs become laid bare when the stock cooler is removed. Puget Systems' take on the G10 is well worth reading for those who are seeking to cool such GPU beasts.

The G10 is not a good VGA cooling solution for any system in a case that doesn't have at least decent support for water cooling. You need space to mount a 120mm radiator & fan, which is the minimum size of radiator used in AIO water coolers. They combine to be at least 2" thick, which is a lot to mount at a vent. The most practical position is usually the top panel vent, which unfortunately allows a direct noise path to the seated user. Putting it at the front panel, ideally, you'd want the fan blowing out to get the heat out of the case. This means the back panel fan might be better as an intake. If there is much in the way of grills and dust filters in front, the impedance will hurt both cooling and acoustics. Having the front vent be wide open also would hurt acoustics. A pack panel position for the radiator and fan would be ideal, thermally and acoustically, but it's the most difficult position, because both the CPU and the VGA card impinge into that space. The length of the water hoses could also come into play, and those hoses could also impinge on the CPU cooler.

A relevant question is whether the product makes sense from a cost point of view. The lowest priced AIO coolers start at around $50~60 before taxes or shipping. Add the $30 for the G10, and we're at $80~90. Such a setup would probably be better than a similarly priced air-only cooler for VGA cooling as well as overall case cooling (because of the water cooling system's ability to move the heat to the perimeter of the case where it can be efficiently evacuated). But it is more complex, and because of the pump, always likely to be a bit more audible even if the fans can be turned way down.

From the silent computing point of view, AIO water coolers are double-edge solutions for CPU cooling. They promise higher ultimate cooling capability, but at the cost of the pump noise, which always seems worse in quality than a good fan. This assessment changes for VGA cooling because stock coolers are far noisier at high load than the G10 + a decent AIO cooler — at least if it performs as well as the X41. But monster aftermarket VGA coolers may offer better acoustics and perhaps nearly as good cooling. One last thought is that because the heatspreader (or heatsink base) makes direct contact with the GPU die rather than a heatspreader as on a CPU, the relatively mediocre performance we've documented with most AIO CPU water coolers may be irrelevant for VGA cooling. To put it another way, one of the AIO coolers that didn't fare so well in our CPU cooling test might shine on a GPU due to the direct die contact.

Our thanks to NZXT for the Kraken G10 Graphics Adapter samples.

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SPCR Articles of Related Interest:

Recommended Heatsinks
Enermax Liqtech 120X AIO Liquid CPU Cooler
Sub-$20 CPU Coolers: A Reader's Roundup
LEPA LV12 Direct-Touch Heatsink
NZXT Kraken X31 & X41 Liquid CPU Coolers
Noctua NH-D15: Update to an Icon

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