Noctua NH-U12S Review
Performance and Testing
The test set up consisted of the following
Intel i7 3960X Stock@ 1.1v (undervolted) 4.0GHz @ 1.25v 4.4GHz @ 1.35v 4.6GHz @ 1.45v Gigabyte X79 UD3 Corsair Vengeance LP Memory Corsair HX850 V2 Corsair Force GT 60GB Coolermaster Storm Trooper.
As usual we'll be testing our coolers at varying levels of overclock and increasing levels of voltage. this in turn of course means increasing levels of heat which the coolers need to dissipate. To begin with we start with the undervolted stock speed. Why undervolted? well if you have things set on "Auto", you may well be using more volts than are actually required to run at the chosen frequency, for example our 3960s will run quite happily at just 1.1volts, solid as a rock, 24/7, and as such we use this as our starting point.
Continuity is very important in testing, and for this reason we keep as many of the potential variables as locked down as possible. We will be using OCCT in Linpack X64, AVX compatible with all logical cores tested and 90% free memory utilised. The test is set up to run automatically with just a few clicks to set it going. A 10 minute idle followed by 30 minutes of testing and a 5 minute cool down is the order of the day and brings the total test time per clock speed to 45 minutes. So as to remove subjectivity in determining whether a CPU has failed, OCCT is set to stop the test and register a fail should the max temp exceed 80 degrees. In testing we noted that if even just one of the cores exceeds 82 degrees OCCT halts the test and a fail is recorded.
As with the 14S we looked at recently we've tested the heat sink in single and dual fan set up. An LNA is supplied, which will, as the name suggests lower the noise. If you choose to use this then you can expect a 2-3 degree increase in temps. We felt though as the set up is so quiet anyway the LNA was largely superfluous and have not tested with it.
The very first thing that sticks out here is that in single fan mode the smaller U12S has actually posted cooler temps than it's bigger brother, the U14S. We're putting this down to the U12S having the NF-F12 focussed flow fans with a higher static pressure of 2.61mH20 as opposed to the NH-U14S's use of the NF-A15 fan with a much lower static pressure of 1.51mH2O. Both heatsinks are clearly able to conduct the little heat generated at this overclock equally well up the fin stack but it's the focussed flow fan that is able to push the heat out of the cooling fins. The second odd thing here is that the cooler actually performs slightly better in single fan set up than dual fan set up at this level of overclock. You'd think that the 1.2 degree discrepancy might be put down to inaccuracies in testing, and to be honest we had our doubts also, and so conducted each of the tests with single and dual fan set up 3 times. We also tried with and without the extra thick rubber spacer supplied for use with the second fan, (this we found to have no effect what-so-ever). The results were the same each time, the single fan set up was consistently slightly better than the dual fan set up.
Turning now to the 4GHz test we up the voltage to 1.25 volts, this is what is deemed normally as stock volts. Something we are always harping on about on the forums is AUTO does not mean stock volts, and normally if you overclocking with "auto" volts the motherboard will be upping the volts much more than needed if you were to do it manually. By whichever means it happens, upping the volts (especially from our 1.1v undervolt) does have a big impact on temps, with an average increase of 10-15 degrees seen in the results.
At the higher levels of heat generated by the increase in voltage required for the 4.0GHz overclock, fan performance, although still a factor becomes less critical, replaced instead by a coolers ability to conduct the heat up the heat pipes and more crucially the total surface area of the fins enabling convection to the atmosphere. The dual fan set up now performs slightly better than the single fan set up, but only by 1.3 degrees, with U12S now 3-5 degrees off the pace of the larger U14S. 3 degrees cooler than the Eisberg 120L on it's lowest fan setting which due to the pump noise was considerably noisier. The single fan configuration was also 4 degrees cooler than the Alpenfohn K2 on its low fan setting. When compared to coolers of it's own size and shape the U12S fares slightly better than the Matterhorn Pure, being some 5 degrees cooler in single fan set up, but not so well against the Megahallem Black which pipped it by 0.5 of a degree, again with both in single fan configuration.
That unfortunately is where the testing stopped, with the U12S unable to make the grade at the 4.4GHz and franky ridiculous 4.6GHz tests. We don't see this as a failing really, remember this is only a 45mm thick tower cooler. We've had AIOs fail at this level.