Thermal Compound Roundup - March 2011
By Rafael Otto Coelho on March 1, 2011
Following up our Thermal Compound Roundup - February 2011 review, we are adding another five thermal compounds to our roundup, for a grand total of 10 different models from Cooler Master, Coolink, Deepcool, Evercool, Gelid, Noctua, Prolimatech, Spire, Thermalright, and Zalman. In this review we will see if certain products are better than others and, also, if the thermal grease curing time is a reality or pure myth.
For a better understanding on how the thermal compound (a.k.a. thermal grease or thermal paste) works and how to correctly apply it, please read our How to Correctly Apply Thermal Grease tutorial. The most important thing that you have to have in mind is that it is a mistake to think that the more thermal grease you apply, the better. The thermal compound is a worse heat conductor than copper and aluminum (the metals usually found on cooler bases). So, if you apply more thermal compound than necessary it will actually lower the cooling performance instead of improving it.
In Figure 1, you can see the five new thermal compounds we are adding to our roundup.
Let's get a closer look at the new contenders in the next pages.
We will now take a look at the five new thermal compounds we are including in our roundup. The first compound in this batch is the Gelid GC Extreme thermal grease, shown in Figure 2 and 3. It is a gray compound.
In Figures 4 and 5, you can see our second thermal compound on this test, the Coolink Chillaramic. It is a white compound.
We also tested the Deepcool Z9 Thermal compound, which you can check in Figures 6 and 7. Its color is dark gray.
In Figure 8, you see the Noctua NT-H1 gray thermal compound. It comes with the Noctua NH-D14 CPU cooler and with other coolers from this brand.
Finally, in Figure 9, you can check our last new contender, the Thermalright "The Chill Factor" white thermal compound.
For a detailed look at the other thermal compounds included in this roundup, please check our Thermal Compound - February 2011 review.
We tested the thermal compounds using the same testbed system that we currently use to test CPU coolers, which is fully described below. Our Core i7-860 (quad-core, 2.8 GHz) CPU, which is a socket LGA1156 processor with a 95 W TDP (Thermal Design Power), was overclocked to 3.3 GHz (150 MHz base clock and 22x multiplier), and we kept the standard core voltage (Vcore). We used a Zalman CNPS9900 MAX CPU cooler, and the only different part in each test was the thermal compound itself.
We measured temperature with the CPU under full load. In order to get 100% CPU usage in all threads, we ran Prime 95 25.11 (in this version, the software uses all available threads) with the "In-place Large FFTs" option. For each test, we applyied the same quantity of thermal compound (about the size of a grain of rice) at the center of the CPU, as shown in Figure 9.
After each test, we check the base of the cooler, making sure the quantity of thermal compound was optimal. The thermal compound must spread evenly on the metallic part of the CPU, without exceeding it, creating a thin layer. The "fingerprint" shown in Figure 10 shows that the compound was properly applied.
Room temperature measurements were taken with a digital thermometer. The core temperature was read with the SpeedFan program (available from the CPU thermal sensors), using an arithmetic average of the core temperature readings. During the tests, the left panel of the case was open.
We also tested the system with no thermal compound on the CPU.
Operating System Configuration
Since both room temperature and core temperature readings have 1 °C resolution, we adopted a 2 °C error margin, meaning temperature differences below 2 °C are considered irrelevant.
The table below presents the results of our measurements.
|Thermal Compound||Room Temp.||Core Temp.||Differerence|
|No Thermal Compound||26 °C||88 °C||62 °C|
|Zalman ZM-STG2||24 °C||59 °C||35 °C|
|Prolimatech Thermal Compound||24 °C||56 °C||32 °C|
|Cooler Master Thermal Compound Kit||23 °C||58 °C||35 °C|
|Evercool EC420-TU15||22 °C||57 °C||35 °C|
|Spire Bluefrost||22 °C||58 °C||36 °C|
|Gelid GC Extreme||26 °C||61 °C||35 °C|
|Coolink Chillaramic||26 °C||61 °C||35 °C|
|Deepcool Z9||26 °C||61 °C||35 °C|
|Noctua NT-H1||26 °C||61 °C||35 °C|
|Thermalright The Chill Factor||26 °C||63 °C||37 °C|
In the graph below, at full load you can see how many degrees Celsius hotter the CPU core is than the air outside the case. The lower this difference, the better is the performance of the thermal compound.
Some people talk about a "curing time", which is the time after installing the cooler (and, obviously, after applying the thermal compound) that the thermal compound takes to reach its best performance.
Well, we performed some tests in order to discover if a thermal compound really performs better after some time. First, we tested the Noctua NT-H1 thermal compound soon after applying it, using the methodology described before, and then we repeated the measurement 24 hours later, and during this time we left our computer running with the CPU fully loaded. Of course, we didn't remove the cooler between the tests. The results are shown in the table below.
|Curing time||Room Temp.||Core Temp.||Temp. Diff.|
|none||26 °C||61 °C||35 °C|
|24 h||26 °C||61 °C||35 °C|
We did a similar test with the Spire Bluefrost thermal compound, this time allowing a seven-day curing time, using the same methodology, i.e. with the CPU working at 100% load between measurements. The results are shown below.
|Curing time||Room Temp.||Core Temp.||Temp. Diff.|
|none||22 °C||58 °C||36 °C|
|7 days||26 °C||62 °C||36 °C|
Our results were very consistent and debunks the myth that "all thermal compound need some curing time to achieve its best performance", at least with the selected thermal compounds. There may be a thermal compound around that actually takes some time to performs at its best, but it seems to be the exception, and not the rule.
With ten thermal compounds tested, our previous conclusions regarding thermal compounds are still valid: there is no significant performance difference between thermal compounds, at least not with the models we included in this roundup. We will continue to add more thermal compounds to our roundup and publish our findings.
This time we decided to include the CPU temperature without any thermal compound at all (actually, using the air as thermal compound), and our results show that the thermal compound is essential for a good cooling performance.
We also debunked the "curing time myth": at least with the compounds we tested, the performance of a recently-applyied thermal compound was the same as after the "curing time". We cannot claim that no thermal compound needs this curing, but the "curing time" seems to be a negligible factor when testing CPU coolers or thermal compounds.