Cooler Master MasterAir Pro CPU Heatsink Roundup

The Cooler Master MasterAir Pro 3 and 4 are designed to fit Intel Socket LGA2011 / 1366 / 1156 / 1155 / 1150 / 775 and most all AMD processors including AM3+ through FM1. Here is an overview of the system and testing methodology.

Asus P8Z68 Deluze Gen3 Intel Z68 Chipset
Intel Core i7 2600K (3.5Ghz) Quad Core 4 x 256KB L2 Cache 8MB L3 Cache

Cooler Master MasterAir Pro 3
Cooler Master MasterAir Pro 4
Intel OEM Heatsink

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 7 task manager reported 100% processor usage we could never attain a 100% of the rated heat output as documented by Intel (see below) 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

MasterAir Pro 3 - 0.35 C/W = (50C - 22C)/(.85(95W))
MasterAir Pro 4 - 0.25 C/W = (42C - 22C)/(.85(95W))

For this next test the CPU speed was cranked up to 4.5Ghz and the test was re-run.

ocC/W = dCPU Watts * (ocMhz / dMhz) * (ocVcore / dVcore)2
ocMhz = 4500
dMhz = 3500
ocVcore = 1.3
dVcore = 1.2
The variance still applies for our C/W calculation
Allowed variance for this test = 85%
CPU Watts = 143W

MasterAir Pro 3 - 0.33 C/W = (62C - 22C)/(.85(143W))
MasterAir Pro 4 - 0.26 C/W = (54C - 22C)/(.85(143W))

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)

The charts show an interesting progression and as you would expect the smaller MasterAir Pro 3 operates at a higher temperature but has a consistent C/W rating between the stock and overclocked configurations.  This indicates that we are still within the thermal limits of the cooler.  You will notice a drop in overclocked C/W which can be attributed to the Turbo PWM fan profile responding to the rise in CPU temp.  The fan was maxed out when overclocked so while the numbers indicate we have headroom we will run out of fan.

MasterAir Pro 4 is the real surprise showing constant numbers across both tests.

It should also be noted that we did test this heatsink using all fans spinning under the Asus Turbo PWM fan profile.  This profile is a little more aggressive than the default enabling them to spin up faster under load.  Both coolers have an option to install a second fan which can really help lower overall load temperatures but can also double the noise output.

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.