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Thermalright HR-01-K8 CPU Cooler

Date: July 12, 2006
Author(s): Rob Williams

In the prospect of building a quiet PC, cooling the CPU can prove to be a problem. To take care of this ‘tall’ order, Thermalright brings us the HR-01. This passive cooler requires no fan at all to operate. If overclocking suits your fancy, they even offer a duct!


Over the past few years, we have seen many tower coolers released, but each has been unique in its own right. The first tower cooler that I used was the Scythe Katana. That was more like the Tower of Pisa though. The cooler I am taking a look at today is from Thermalright, one of the world leaders in CPU cooling products.

The HR in the name stands for High-Riser… appropriately named. This is not a small cooler.. it comes in at near 16cm high. Why the large stature? The HR-01 is designed to perform well without the use of any fan. Of course, to help aide the warm air out of the computer, we need to use a duct. Before we get into the inner workings, let’s take a quick glance at the features.

The cooler arrived in a clean brown cardboard box. Simple, the way I like it. The first thing I pulled out was a small white box which included the accessories. Inside that was thermal paste, a sticker, instructions and the K8 clip. I received the 775 version of the cooler so to get it to work on my 939, I just had to remove the plastic clips off the base of the cooler.

As you can see, this is one sturdy looking cooler. Simply holding it in your hands quickly tells you that it’s a well built unit. I don’t think hurling it at a wall would dent it! Not that I am going to try, since I like living here. Anyways, the cooler follows the standard ‘tower’ design, by being tall with many fins. The base of the cooler has heatpipes, which lead up through the fins, to dissipate heat quickly and efficiently.

Features, Installation

The top of the cooler is different than other tower coolers on the market though. Rather than be completely flat with pipes protruding through, there are notches all the way up, through each fin. This is obviously designed to dissipate heat through the top, and not only the sides.

Despite the silver theme, the base and heatpipe are comprised of copper. All of the fins are aluminum, however.

Because this is a passive cooler, it’s highly recommended that you also purchase the fan duct. If you are not overclocking your CPU at -all- though, you may not need to worry. I will get more into the duct and it’s function during my installation report.


Installing the HR for me was going to be interesting because I received the 775 version of the cooler. To modify, I just had to break off the plastic clips and remove the 775 bracket. Incredibly easy to do… surprisingly.

To be honest, I really had to idea how it was supposed to be installed. I received the 775 instructions, not the K8, so I was left on my own. After cleaning off the CPU, I pretended to install the cooler to see how it was supposed to fit. The included bracket is completely different than any I have ever seen, so I was unsure just how it was supposed to be installed.

During installation, I admit I was getting frustrated. I felt I was applying far too much force to the clip, and it still was not secured. When I finally did get it installed, it was a tad easier than the first few times I tried, but I am unsure why. The most tedious part was reaching my finger in the small space to push hard on the clip to lock it into place. There were a few occasions where I almost cut myself on the PWM heatsinks nearby.

After the cooler was installed, the next step was the duct. The duct attaches itself to one side of your cooler and the opposite end of the duct is supposed to be attached to the 120mm exhaust fan at the back of your PC. Though there are no preset screwholes in the duct, you are supposed to pierce threw to screw it into place. Because this is a completely passive cooler, the duct is designed to route the warm air through and out the back quickly. The 120mm is a large fan, so it does a great job of performing the task at hand.

Now as I mentioned, the duct is meant to be screwed onto the fan, and then the other end attached to the heatsink. I found this an impossible job to perform in my case, if I ever wanted it to look decent. Not only that, but trying to stretch the duct to such a degree, would be far more of a problem than it’s worth. So as you can see, I have the duct going straight across, taking up half the fan. In your case, if your CPU socket is better aligned with the fan, you should have no problem installing it the way it’s designed to.

After the arduous chore of the installation, I am happy with how it turned out. This looks like a solid passive cooling solution, but the testing will be the proof of that…

Testing, Conclusion

To test out the cooler, I ran an instance of SuperPi and Prime95 (Small FFT) at the same time, for 30 minutes. I ran the tests with and without the duct, at both 2.0GHz and 2.7GHz. Prior to installing the HR-01-K8, I ran the same tests using the Corsair Nautilus 500 water cooling system. There’s no doubt that this water cooling will be significantly better than the HR, but the goal is to simply show differences. The room temperature during all of the testing hovered between 80°F – 81°F. In between each test, the computer was turned off until the heatsink was cool, so as to start fresh each time.

I am actually quite surprised at the difference that the duct made. Adding it took 9°C off of the 2.0GHz max temp, and 13°C off the 2.7GHz max temp. That is not a small difference! Needless to say, it’s obvious why you will want to use the duct.

The N500 really does clean up in all of the tests, but that’s no surprise. For a passive cooler though, I am -very- impressed with how it held up. Especially because my ambient room temp is so high. It handled the CPU’s 35% overclock without going over 50°C, which I respect.


Obviously this cooler is not for everyone. It caters to the quiet PC crowd, and does it deliver! The only sound coming out of my PC was the 120mm fan in the back and the GPU fan.. so overall it was a very quiet PC. Using the duct proved to help a -lot-, so there is no reason to consider not buying one, unless you are using the cooler in a very small case or don’t plan to have even a minor overclock.

Though I enjoyed the passive performance of the cooler, there are a few things I really didn’t care for. The primary issue being the installation. Looking past the lack of instructions, I found I really had to force the cooler in to place, which never sits right with me. I almost cut myself, and thought I was going to damage the board.

The cooler is also so tall, that my case door will not fit back on. If the cooler was half an inch shorter, it would be fine. It really depends on your case, but the NZXT Lexa is not an extra small case by any means. The same goes for the duct also though. With it installed, I have to force the door back on. If your case does not have a fan in the door, you should be 100% ok. Just bare in mind, that a door fan will likely get in your way, if it aligned up with the CPU socket remotely close.

Regardless, if you are a ‘fan’ of passive cooling, and have a case that will house this beast, you will do good to pick one up. I am awarding the HR-01 an 8 out of 10.

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