Temperatures & Acoustics / Power Consumption
For all temperature testing, the cards were placed on an open test bench with a single 120mm 1200RPM fan placed ~8” away from the heatsink. The ambient temperature was kept at a constant 22°C (+/- 0.5°C). If the ambient temperatures rose above 23°C at any time throughout the test, all benchmarking was stopped. For this test we use the 3DMark Batch Size test at its highest triangle count with 4xAA and 16xAF enabled and looped it for one hour to determine the peak load temperature as measured by GPU-Z.
For Idle tests, we let the system idle at the Windows 7 desktop for 15 minutes and recorded the peak temperature.
HIS’s IceQ X² heatsink allows for extremely low temperatures when the two cards are at stock speeds and that doesn’t change too much when higher clock speeds are applied. These are actually quite impressive results since it proved this heatsink isn’t operating anywhere near its thermal limits.
What you see below are the baseline idle dB(A) results attained for a relatively quiet open-case system (specs are in the Methodology section) sans GPU along with the attained results for each individual card in idle and load scenarios. The meter we use has been calibrated and is placed at seated ear-level exactly 12” away from the GPU’s fan. For the load scenarios, a loop of Unigine Heave 2.5 is used in order to generate a constant load on the GPU(s) over the course of 20 minutes.
There are a number of things we have to point out here. First and foremost, both cards’ heatsinks operate at extremely low decibel levels but a stock speeds HIS’s high efficiency PWM’s noise output actually outstrips the fans. When higher clock speeds are used, the fans do increase their speed but not to a level which will be noticed over ambient gaming noise.
Will you actually hear the PWM wailing away when in game? That all depends on how loud the volume is cranked. At reasonably levels, there’s just no way it would intrude so we won’t let this detract from an otherwise excellent experience. Just be aware that the PWM’s acoustical profile is quite high so it will be distracting for some people.
System Power Consumption
For this test we hooked up our power supply to a UPM power meter that will log the power consumption of the whole system twice every second. In order to stress the GPU as much as possible we once again use the Batch Render test in 3DMark06 and let it run for 30 minutes to determine the peak power consumption while letting the card sit at a stable Windows desktop for 30 minutes to determine the peak idle power consumption. We have also included several other tests as well.
Please note that after extensive testing, we have found that simply plugging in a power meter to a wall outlet or UPS will NOT give you accurate power consumption numbers due to slight changes in the input voltage. Thus we use a Tripp-Lite 1800W line conditioner between the 120V outlet and the power meter.
While the PWM does pump out some excess noise, there is some reasoning behind HIS’s madness. As our power consumption numbers show, these are some extremely efficient cards at both stock and overclock speeds.
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