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ID-Cooling IS-25i Review


Here at Lini PC we are frequently in the lab testing out new components. Cooling ultra compact Mini-ITX systems is the biggest challenge we face so we have tested literally every Mini-ITX cooling solution on the market.

One vendor that came across our radar several months back is ID-Cooling and we finally had time to do some rigorous testing of several of their cooling solutions.

We have been using the Zalman CNPS2X for Lini PC since we started and it outperforms every other very low profile cooler we have tested.

To be clear, there are very few coolers on the market that can fit into a system as compact as the Lini PC, and you can't expect miracles.

Cooling is all about surface area and air flow. The larger a heatsink is the more surface area there is for heat exchange. The large a fan is the more air flow there is.

An ultra compact heatsink-fan unit will always be limited by the factors of surface area and air flow and a tiny low profile heatsink with an 80mm fan is never going to perform like a big tower with a 120mm fan strapped to it.

Today we tested the ID-Cooilng IS-25i and compared it to the Zalman CNPS2X to see if we could find a new champion in the field of ultra-compact Mini-ITX cooling.

ID-Cooling IS-25i

The ID-Cooling IS-25i measures only 27mm in height, which makes it perfect for a 60mm case like the Lini One.

The heatsink has two direct touch heat pipes. The base has a reasonably clean finish, but it is not at a mirror level of polish.

The IS-25i has an 80x10mm ball bearing fan. The heatsink and fan weighs 5.7 ounces on our scale.

ID-Cooling has another model called the IS-25 which is also compatible with AMD motherboards. If you are using an Intel motherboard definitely get the IS-25i which is both less expensive and has an easier to use mounting mechanism than the IS-25.

IS-25i Compared to Zalman CNPS2X

The CNPS2X features Zalman's typical round design, which is not bad in a larger heatsink, but in this case the rectangular IS-25i appears to have more overall surface area.

Zalman's offering has only a single direct touch heat pipe as opposed to two on the IS-25i. The heat pipe on the Zalman unit is not perfectly flush with the base of the heatsink which creates a gap between the rest of the heatsink base and the CPU.

Overall, the finish, size, and contact of the IS-25i base appears to be superior to the CNPS2X.

Like the IS-25i the CNPS2X has an 80x10mm fan.

Once major annoyance we have encountered with the CNPS2X fan is that it is pressure fit, and it has come out multiple times in shipping, resulting in returned systems. By comparison the fan on the IS-25i is securely screwed in place.

The CNPS2X weighs 3.7 ounces on our scale, 2 ounces less that the IS-25i. All else being equal, weight is an advantage when it comes to heatsinks, and this is another win for ID-Cooling.

Testing Procedures

We do not do any really fancy testing process because for the most part a few degrees difference is not going to be noticeable. We are looking for the kind of major performance differences that will be noticeable to our end users, not just numbers for a chart.

Due to the joys of working in a Southern California garage with no air conditioning these tests were performed with an ambient temperature of roughly 35C (95F) which is a much higher ambient temperature than you will see in most product reviews.

We performed all tests in the open air with no additional case fans used. The fans were run at full power settings in the BIOS at all times.

The other components used in the test were an ASRock Z97E-ITX/ac, an Intel Core i7-4790S CPU, and 16 GB DDR3 1600 Memory. We used an EVGA 430 Watt 80 Plus power supply for testing.

We performed these tests using the Xubuntu 15.04 Linux operating system. We used the lm-sensors package to monitor temperatures and we used Prime95 to stress test the CPU and cooling solutions.

Neither of these coolers can cool the Core i7 sufficiently to run Prime95 in Torture Test mode without throttling so our testing methodology was to start from the lowest idle temperature we could achieve and see how long each heatsink and fan could keep the CPU running without throttling.

Test Observations

When running Prime95 with 8 threads, fully utilizing all 4 cores, the i7-4790S will stay steady at 3.6 GHz on all cores until thermal throttling kicks in.

When Prime95 starts in the default Torture Test mode it begins with an FFT length of 320K, which results in more memory utilization and less CPU utilization, and a total system power draw of around 90 watts.

When Prime95 switches to running an FFT length of 8K total system power consumption jumps to around 116 watts.

Test Results

  Fan Speed FFT Length Idle Temp
Max Temp
Time to > 80C Time to Throttle
Zalman CNPS2X 2800 RPM 320K 39C
Over 80C
1 Minute 2 Minute
ID-Cooling IS-25i 3100 RPM 320K 40C


The improvement of the ID-Cooling IS-25i over the Zalman CNPS2X turned out to be very significant.

When faced with the Prime95 torture test in a very challenging environment the CNPS2X leapt to over 80C in a minute and began throttling after only 2 minutes.

By comparison the IS-25i was able to stabilize at 78C for 8 minutes and never throttled while running the 320K FFT Length test.

Once the 8K FFT Length Test began and system power usage jumped from 90 to 116 watts the IS-25i quickly succumbed and the CPU began throttling.


The ID-Cooling IS-25i offers a major advance in cooling performance over the Zalman CNPS2X which was previously the best ultra low profile Mini-ITX cooler that we had tested.

The IS-25i has numerous design advantages including dual heatpipes, greater surface area, greater weight, and better finish and CPU contact. All of this pays off with a significant advantage in real world performance.

We will be building all of our high end ultra compact Lini One systems with the IS-25i in the future and we strongly recommend this product for DIY builders of similar systems.

We also had a chance to test the larger ID-Cooling IS-40 and their somewhat unique vapor chamber based cooler the IS-VC45. We compared these two coolers to the high end Noctua NH-L9i and the results were surprising, so stay tuned for that report coming soon.

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