bequiet Pure Loop AIO Watercooler Review

The bequiet Pure Loop 280mm is designed for use on Intel Socket LGA2011 / 2066 / 1200 /  1156 / 1155 / 1150 and AMD processors. Below is an overview of the system and testing methodology.

MSI Z390 Ace – Z390 Chipset
Intel Core i9 9900k (3.6Ghz) Octo Core 8 x 256KB L2 Cache 16MB L3 Cache

bequiet Pure Loop 280mm
Cooler Master MasterLiquid ML280 Mirror
SilverStone PF240-ARGB

The CPUID System Monitor was used to obtain and record system temperature data and being that this is a quad core processor we need something that will work across all of the cores at once.  For this task we're using a new version of Prime95 (p95v255a) that will allow you to spawn (n) instances to test with.

Editors note: Even though the Windows 10 task manager reported 100% processor usage we could never attain a 100% of the rated heat output as documented by Intel when using Prime95 as a basis for that heat production. Knowing this we ran the stress test until the maximum temperature was attainted and stabilized.

Other things to consider when judging software induced heat output.

a) Clock throttling by the processor at high temperatures.
b) Normal software isn't designed to produce maximum heat output.
c) Variances of cooling temperature.
d) Variances in CPU load.
e) Inaccuracies in thermal diode readouts.
Of course the list goes on..

Our testing methodology is aimed to provide a real world look into this heatsink given the test system provided.

A C/W rating can quickly be calculated using this formula.

C/W = (CPU temp - Ambient temp)/(Variance(%) * CPU Watts)
Allowed variance for this test = 85%
CPU Watts = 95W  (or 124W due to turbo clock)

0.32 C/W = (56C - 22C)/(.85(124W))

For this next test the CPU speed was cranked up to 5.3Ghz and the test was re-run.

To calculate a new C/W rating for this test we will need to factor in the increased processor wattage. The formula and constants for this are listed below.

ocC/W = dCPU Watts * (ocMhz / dMhz) * (ocVcore / dVcore)2
ocMhz = 5300
dMhz = 4700 (boost)
ocVcore = 1.4
dVcore = 1.2
The variance still applies for our C/W calculation
Allowed variance for this test = 85%
CPU Watts = 190W

0.32 C/W = (74C – 22C)/(.85(190W))

In our heatsink and waterblock tests we don't really focus on overall load temperatures but rather how well the product can remove heat given a specified heat load. Since this is a real world testing method we need to take into consideration real world variables and estimate tolerances. This is why we normally only apply 85% of the total wattage output to our heat calculations.

The resulting C/W number is used to rate how efficient a heatsink or waterblock is based on the given heat load. These numbers can be used to determine heat capacity, the larger the difference the less efficient the heatsink is. (aka not good for overclocking)

It has been a long while since I had a cooler that tested equally well at both the default speed and the overclocked one.  This indicates that the cooler can handle a higher load and that the unique design it working well.

Keep in mind these calculations are provided for demonstration purposes only and may not reflect the actual lab tested C/W rating, but we're pretty close.