Cooler Master V6 GT Heatsink Review

The Cooler Master V6 GT is designed for Intel Socket LGA1366 / 1156 / 775 and Athlon 64 processors. Here is an overview of the system and testing methodology.

EVGA X58 LE Intel X58 Chipset
Core i7 920 (2.66Ghz) 4 x 256KB L2, 8MB L3 Cache 4.8GT/s QPI
Cooler Master V6 GT
OEM Heatsink

The E-LEET tuning utility 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 = 130W

0.13 C/W = (39C - 25C)/(.85(130W))

For this next test the FSB was cranked up to 180Mhz 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 = 3800
dMhz = 2660
ocVcore = 1.35
dVcore = 1.20
The variance still applies for our C/W calculation
Allowed variance for this test = 85%
CPU Watts = 235W

0.17 C/W = (58C - 25C)/(.85(235W))

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)

Here we have a heatsink that can clearly handle and overclocked system at over 200W of power.  In these tests you'll notice that the C/W numbers went up between the default and overclocked tests.  All this indicates is that we are approaching the thermal limit of this cooler, which also happens to be the advertised capacity. 

It should also be noted that the numbers shown here are with both fans spinning at 2300rpm.  As a sanity check we did test this heatsink using only a single fan and found the load temperature to only increase by 3 degrees during our overclocking test. Not bad considering.

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.