CPU Cooler Test Methodology
CPU cooler testing is conducted using the bench defined below. We use a bench that is more carefully crafted for noise performance, opting for a passively cooled PSU and 23% RPM 980 Ti blower fan for very low system noise.
We strongly believe that our thermal testing methodology is among the best on this side of the tech-media industry. We've validated our testing methodology with thermal chambers and have proven near-perfect accuracy of results.
Conducting thermal tests requires careful measurement of temperatures in the surrounding environment. We control for ambient by constantly measuring temperatures with K-Type thermocouples and infrared readers. Two K-Type thermocouples are deployed around the test bench: One (T1) above the bench, out of airflow channels, and one (T2) approximately 2-3" in front of the cooler's intake fan. These two data points are averaged in a spreadsheet, creating a T3 value that is subtracted second-to-second from our AIDA64 logging of the CPU cores.
All six CPU cores are totaled and averaged second-to-second. The delta value is created by subtracting corresponding ambient readings (T3) from the average CPU core temperature. We then produce charts using a Delta T(emperature) over Ambient value. AIDA64 is used for logging thermals of silicon components, including the CPU and GPU diodes. We additionally log core utilization and frequencies to ensure all components are firing as expected. Voltage levels are measured in addition to fan speeds, frequencies, and thermals.
The cores are kept locked to 3.8GHz (x38 multiplier). VCore voltage is locked to 1.141v for the CPU. C-States are disabled, as is all other power saving. The frequency is locked without any interference from boost or throttle functions. This is to ensure that the CPU does not undergo any unexpected/uncontrollable power saving or boost states during testing, and ensures that the test platform remains identical from one device to the next.
Fan speeds are manually controlled unless otherwise defined. For liquid coolers, pumps are set to 100% speed unless otherwise defined.
No open bench fans are used for these CPU cooler tests. Only fans which are provided with the cooler are used.
|GN Test Bench 2015||Name||Courtesy Of||Cost|
|Video Card||GTX 980 Ti Reference 23% RPM||NVIDIA||EOL|
|CPU||Intel i7-5930K CPU @ 3.8GHz||iBUYPOWER
|Memory||Corsair Vengeance 32GB 2666MHz||Corsair||$175|
|Motherboard||EVGA X99 Classified||GamersNexus||$365|
|Power Supply||Enermax DigiFANLESS||Enermax||$250|
|SSD||HyperX Savage SSD||Kingston Tech.||$130|
|Case||Top Deck Tech Station||GamersNexus||$250|
|CPU Cooler||This is what we're testing!||-||-|
We use an AMPROBE multi-diode thermocouple reader to log ambient actively. This ambient measurement is used to monitor fluctuations and is subtracted from absolute GPU diode readings to produce a delta value. For these tests, we configured the thermocouple reader's logging interval to 1s, matching the logging interval of GPU-Z and AIDA64. Data is calculated using a custom, in-house spreadsheet and software solution.
Our test starts with a 180s idle period to gauge non-gaming performance. A script automatically triggers the beginning of a CPU-intensive benchmark running Prime95 LFFTs. Because we use an in-house script, we are able to perfectly execute and align our tests between passes.
Noise Normalized Thermals @ 40dBA
We’ve been testing noise-normalized thermals on liquid coolers for a few years now. This metric allows us to equalize all coolers to the same noise level – 40dBA in a room with a noise floor of 26dB – and so we can establish the most efficient coolers of the bunch. The nature of cooling is that any of these devices could leap to the top of the charts simply by running faster, louder fans, but it’s not exactly fair to proclaim a cooler as being “best” just because it might have Delta fans that go 4000RPM. Clearly, in this ridiculous example, such a cooler would have the best thermals, but would otherwise have untenable noise levels. For this reason, we run one test with coolers all set to the same 40dBA, which results in this chart.
The EVGA CLC 360 runs about 40dBA when its fans are all set to roughly 1020RPM, with the pump still running at max speed. The CLC 360 ends up at about 35-36 degrees Celsius over ambient. It’s been a little while since we’ve run a CLC review, so as a reminder, these numbers are over ambient, meaning we’re taking a delta of the averaged CPU core temperature and the ambient temperature as logged second-to-second. The CLC 360 is within error margins of our 40dBA normalized results for the Kraken X62 at 1200RPM. At this point, we’re within measurement error of the X62, the Phoenix 360, and the H150i. The difference, as always, is now how much additional headroom there is to boost fan speeds and pull-down temperature. We’ll look at the 100% fan speed chart for that.
Max Fan Speed
With everything set to max fan speeds, the EVGA CLC 360 and its three deafening 60.4dBA 2550RPM fans manages the best result, at 31.7 degrees Celsius over ambient. This really shouldn’t surprise anybody, at this point, as it’s the loudest cooler on the bench only after other EVGA CLC products. The CLC 360’s 32-degree result has it slightly better than the 33-degree result on the CLC 280 with two 2200RPM 140mm fans. For most users, meaningful differences don’t really emerge until we get all the way down to 240mm liquid coolers, like the Kraken X52 at 2100RPM and 37 degrees, but that’s why we do the noise normalized testing. At a given noise level, the CLC 360 will always do significantly better than those 240mm coolers. If you’re looking for a lower fan RPM to achieve the same thermals, increasing radiator size will almost always help. There are times it doesn’t, but only when the pump is anemic. That’s not the case here.
Noise levels will close us out. We already had a look at 40dBA performance, but if you’re wondering what the previous result costs in terms of noise, it’s a lot. At 60.4dBA, the CLC 360 is the loudest on the chart, approached by the CLC 240, to no surprise, really. Adding an extra fan pushes noise up a little bit.
The EVGA CLC 360 is brand new, although the CLC series has been around for a while now. The EVGA CLC series uses a Gen5 Asetek pump, which has the older impeller than the newer Gen6 metal impeller, but also tends to perform marginally better in thermals. Other coolers in this price bracket include the NZXT X62 280mm liquid cooler, priced at about $140, the Deepcool Castle 360EX at $160, and the Corsair H115i Pro 280mm cooler at $140. The EVGA CLC 360’s value isn’t quite as strong as the launch value of the EVGA CLC 280, but still a fine product – it’s just more clearly embattled by nearby solutions. At this price, you’re mostly choosing between the look of the product.
Editorial, Testing: Steve Burke
Testing: Jake Henderson
Video: Josh Svoboda, Andrew Coleman