by Sergey Lepilov
02/25/2009 | 07:01 PM
Home Theater Personal Computer (HTPC) systems become more and more popular. The key features of these systems are compact size and noiseless operation. Therefore, cooling systems for processors installed in HTPC platforms also have to meet special requirements: the coolers have to be low-profile and generate minimal noise or work in passive mode (without any fans). Well-known Thermalright Inc. designed a cooling solution like that. It turned out, Thermalright AXP-140 boasts not only 70.2mm height, but also operates almost completely noiselessly. But let’s start our story about this cooling solution from the very beginning.
The cooler is shipped in a medium sized cardboard box with minimum of info on it: just the manufacturer name and the cooler model name:
There is a protective polyurethane foam casing holding Thermalright AXP-140 securely inside the box. There is a flat cardboard box with accessories on one side of it:
The new cooler is designed only for LGA775 platforms, that is why Thermalright AXP-140 is bundled only with an LGA775 backplate, four screw-nuts and a wrench for them, two wire clips and two silicon strips for the fans, The Chill Factor thermal interface, installation instructions and a Thermalright sticker. No fan is included with the cooler.
Thermalright AXP-140 cooler measures 145 x 147 x 70.2 mm and weighs 550g.
Only when you take Thermalright AXP-140, you realize how well the cooler is built. An extremely dense array of aluminum heatsink plates sitting solidly on the heatpipes and soldered to them promise reliability and efficiency. The cooler is based on six copper heatpipes with 6mm diameter that go through a copper base:
Note that the heatpipes pierce the base plate through, and not come out of it, like we usually see by most “top-coolers”.
The heatpipes contact the heatsink plates twice. There are two groups, three heatpipes in each. They pierce the entire heatsink array with their one end, go through the base plate, then join together in one tight group and again pierce 42 heatsink plates in the center of the array:
So, the main thermal load will be distributed over the two groups of long heatpipes outside the fan dead zone. And the short heatpipes in the center of the heatsink should be dealing with a much smaller part of the heat flow, in my opinion.
There are 79 plates in the heatsink, each 0.32mm thick. The plates are spaced out at 1.2mm distance from one another. As a rule, heatsinks with such dense plate arrays are very sensitive to the efficiency of the installed fan and its static pressure. It may be not so evident for AXP-140, because its plates are only 25.5mm tall (and only 20mm in the center of the heatsink). Nevertheless, we are going to see how the cooling efficiency of Thermalright AXP-140 solution depends on the fan rotation speed and fan type. Here I would also like to add that the calculated heatsink effective surface area is 4782sq.mm (Thermalright SI-128 SE boasts 6786sq.mm).
I would like to point out that the central group consisting of 6 heatpipes doesn’t really pierce the heatsink, but touches it only with its upper part. There are 42 additional short 60mm plates soldered to the bottom of these heatpipes that create an impression of a solid heatsink:
Not only this part of Thermalright AXP-140 cooler is soldered through. Every single contact is soldered, including the contact surface between the base plate and the heatpipes.
Moreover, all parts of the heatsink are nickel-plated:
As I have already mentioned above, the cooler boasts the highest quality of assembly. Unfortunately, we can’t say the same about the base – an Achilles heel of mot Thermalright coolers. The nickel-plated surface of the copper base plate is finished OK:
Its evenness, however, is far from ideal:
As you can see, there is a small bump in the center of the base plate that is also shifted a little to one side. You can see it even better from the thermal compound imprint left by the even CPU heat-spreader when the cooler was installed and fastened with its bundled retention:
Of course, this imprint cannot compare against impeccable imprints left by Scythe or Thermaltake coolers, but it is very decent for a Thermalright cooler, I have to say. That is why we didn’t make any manual improvements of our own this time. I would also like to add that the thinnest part of the copper nickel-plated base plate measures 2.1mm.
Thermalright AXP-140 installs only on LGA775 mainboards (as I have already said this new cooler is compatible with only one socket type) in a fairly simple manner (you can download the installation instructions here: PDF-file, 878KB). Since the cooler retention is already installed between the heatpipes above the cooler base, all we have to do is turn the cooler upside down holding on to the retention at the base, put the board on top and then tighten the screws through the backplate:
The cooler is pressed very firmly against the mainboard but the backplate prevents the PCB from bending when Thermalright AXP-140 is installed. This is what the heatsink looks like on the board:
As you can see, it covers the entire area around the CPU socket and hangs 15mm off the edge of the mainboard PCB when positioned this way. Note that it will be extremely inconvenient to plug in the 8-pin power connector, which is usually located in the upper left corner of the PCB.
If you install the cooler the way shown above, the right side of the heatsink will hit against the tall heat-spreader on the memory module in the first DIMM slot:
I had to bend the module a little. I do not recommend doing the same thing even if you happen to have the new Thermalright AXP-140 and tall memory modules. Make sure that your platform is compatible with the new Thermalright AXP-140 before you buy it. There won’t be any problems if the memory modules have regular heat-spreaders or none at all, because there is a 40mm distance fro the mainboard PCB to the lower heatsink plate edge:
But why did I stick to that particular positioning of the new Thermalright AXP-140 on my platform, namely, with the heatpipes ends facing up? Why not turn the cooler so that the heatpipes run parallel to the PCI-E slots on the mainboard? In this case the heatsink wouldn’t hit against the memory DIMMs. Here are a few other examples of how you could install Thermalright AXP-140 inside a system case:
The thing is that when we installed the cooler the way you see on the picture on the left, its efficiency dropped by 8-10°C under maximum CPU load compared with the installation when the heatpipe ends were facing up. What a tremendous difference! However, I wouldn’t hold only the heatpipe ends positioning responsible for it, especially, since the mere principle of any heatpipe functioning implies that there shouldn’t be any dependency like that at all. It will make sense to remember that the cooler base is very uneven and the central contact spot is a little off. It looks like the contact was best for the highest heat transfer efficiency when we installed the cooler with its heatpipes facing up. This is where the significant temperature difference is actually coming from. However, our Thermalright SI-128 SE sample features an almost absolutely even base, but it is also more efficient when installed with the heatpipes facing up. So, we will not completely exclude the dependency on the cooler positioning during installation :)
Thermalright AXP-140 can work with 120 x 120 x 25/38mm fans and 140 x 140 x 25/38mm fans. You should use two wire clips bundled with the cooler to attach any of these fans to the heatsink. This is what Thermalright AXP-140 with a fan looks like inside a system case:
It may also look like this:
By the way, you should better insert the wire clips into the heatsink before you install the mainboard with the cooler into the system case, because the heatsink size may make it pretty difficult to insert these clips once inside the case. Before attaching the fan you should also stick two silicon strips to the heatsink. They will lift the fan above the heatsink a little bit and will also reduce the resistance and lower the noise.
In conclusion to our discussion of Thermalright AXP-140 let me sum up its features and recommended retail pricing in the table below:
Thermalright AXP-140 is already available in retail.
We tested our today’s hero and its only competitor only in a closed system case with a side panel removed. It will allow us to emulate the most common working conditions for this cooler in tower-type system cases. And the removed side panel will minimize the dependency of the cooler efficiency on the specific system case model.
Our testbed was identical for all coolers throughout the test session and featured the following configuration:
All tests were performed under Windows Vista Ultimate Edition x86 SP1. We used the following software during our test session:
So, the complete screenshot during the test session looks as follows:
The stabilization period for the CPU temperature between the two test cycles was approximately 10 minutes. We took the maximum temperature of the hottest processor core of the four for the results charts.
The ambient temperature was checked next to the system case or open testbed with an electronic thermometer with 0.1°C precision that allows monitoring the temperature changes over the past 6 hours. During our test session room temperature stayed at 22.5°C (±0.2°C).
We are going to compare our Thermalright AXP-140 against a cooling solution from the same manufacturer – a well-known Thermalright SI-128 SE, which is currently the most efficient “top” cooler. As we have already mentioned earlier in our review, our SI-128 SE sample had an even base. We didn’t do anything to improve the cooler even more. We used AXP-140 retention to install it onto the testboard, because both these coolers have identically shaped and sized base plates. This allows us to compare the “pure” heatsink efficiency and eliminate any possible influence of the retention type used. The cooler was installed with the heatpipes turned up.
Thermalright SI-128 SE was equipped with Enermax Magma UCMA12 fan that has proven to be the most efficient fan for this type of heatsink. The fan worked in three speed modes: in quiet mode at 840RPM, at 1180RPM generating moderate noise and at 1580RPM generating medium noise. Our tests show that the cooling efficiency of the SI-128 SE cooler improves most dramatically when the fan rotation speed increases to 1600RPM. Any further increase in the fan rotation speed has minimal effect on cooling performance.
As for Thermalright AXP-140, we tested it with two types of fans. Since 140 x 140 x 25mm fans are less widely spread in the market than 120 x 120 x 25mm fans, we decided to find out how efficient AXP-140 would be with the above mentioned Enermax Magma fan at different rotation speeds. As for the 140-mm fan, we chose Scythe Kaze Maru with rotation speed adjusted in the interval from 500 to 1900RPM. The new cooler is not designed to work in passive mode (without fans), because the heatsink array is too dense, that is why we didn’t perform any tests like that.
We are going to start with a not quite common diagram. It shows the results obtained with Thermalright AXP-140 with a 140-mm Scythe Kaze Maru fan working at different speeds and with different CPU clock frequency and Vcore settings. The idea behind this test is fairly simple: at first we determined the maximum CPU frequency at the lowest fan rotation speed of 535RPM. Then we increased the fan rotation speed two steps up, by about 300-400RPM each, without overclocking the CPU any further. Then we once again found the maximum CPU frequency for each next fan rotation speed, and so on and so forth. The results were summed up in the following diagram:
As we see, even in the quiet mode at 535RPM fan rotation speed, Thermalright AXP-140 can cope just fine with a CPU overclocked to 3620MHz at 1.45V Vcore running heavy-duty Linpack test. It is a very good result, because the load created by Linpack is sort of unique, the noise from the cooler is minimal and besides, HTPC systems will never work in conditions like that. This allows us to conclude that Thermalright AXP-140 working in quiet fan mode will do perfectly fine with any existing processors.
If you value noiseless systems then you would be really interested in the results obtained at 840RPM and 1180RPM. In the first case, our quad-core processor overclocked to 3825MHz at 1.55V Vcore, which is only 25MHz short of the maximum this CPU can do in Linpack. Further tests with Thermalright AXP-140 didn’t generate any new results, although we could lower the CPU temperature by 4°C and 1°C at 1500RPM and 1860RPM respectively. So, we can state that the new Thermalright AXP-140 cooler becomes more efficient as the rotation speed of the 140-mm fan increases from 840 to 1500RPM. Speeding up the fan further doesn’t really justify the significantly increasing noise.
The next diagram will compare the cooling efficiency of our today’s hero against Thermalright Si-128 SE:
As we remember, Si-128 SE has been so far the best “top” cooler (i.e. a cooler with the airflow directed to the top of the mainboard). Now we can pronounce Thermalright AXP-140 our new leader in this category. It managed to win 2-3°C from the former champion under maximum workload. Yes, the 140-mm fan does play an important role here. When we replaced it with a 120-mm one, the temperature increased by the same 2-3°C. However, a 140-mm fan installed onto a SI-128 SE doesn’t do any additional good (the results are even 1°C worse than with a Magma fan, because Scythe Kaze Maru has a larger rotor and less focused airflow).
But this is also not all yet. In conclusion I would like to offer you the results of maximum CPU overclocking and its thermal readings with each of the today’s testing participants at the maximum fan rotation speeds:
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Both highly-efficient cooling solutions ensured CPU stability at 3825MHz and 1.55V Vcore. However, Thermalright AXP-140 turned out 6°C more efficient in this mode than its counterpart. And although the noise level is 1.1dBA/1m not in its favor, we are still truly impressed.
Let’s start with the drawbacks. In my opinion, there are three of them and they can be lined up as follows in order of significance: support of LGA775 platform only, high price, limited compatibility. First, I couldn’t quite understand why a cooler priced as high as a budget CPU could only be installed on an LGA775 platform? If we take into account that it is positioned for HTPC systems, then it is unclear why these systems can only be based on this particular platform? And what about LGA1366 or AMD solutions? According to Thermalright, the LGA1366 kit is already available separately and eventually will eb included into the accessories buindle. I guess, it will solve part fo the problem, but the question about AMD platform support still remains open. Second, Thermalright coolers have never been cheap, but they pushed it way too far with AXP-140. If they also included a 140-mm fan with a rotation speed controller or at least PWM support as well as retention kits for all contemporary platforms, then the 60-dollar price tag could be justified. And the third drawback - limited compatibility – is not really a drawback, but a warning for potential Thermalright AXP-140 users that they should make sure their mainboard and system case are compatible with it before they buy. Also, don’t forget to check how even the base is (you can use your credit card for that).
Other than that, Thermalright AXP-140 with a 140 x 140 x 25mm fan is the most efficient “top” cooler today. It is not just efficient for CPU cooling, it also works well for the cooling of the area and components around the processor socket, which as a rule improves the overclocking results and system stability. Reliable and simple retention for LGA775 platform protecting the PCB from bending is one of the key advantages of this solution. I should also add high efficiency at low fan rotation speed and very decent efficiency increase at fan rotation speeds up to 1500RPM. The former will be very useful for the owners of quiet (almost noiseless) systems, while the latter will come in handy for non-extreme overclockers. To cut the long story short, we found a new ideal tower cooler a few days ago, and now we have finally found a replacement for the former leader – Thermalright SI-128 SE.
P.S.: We still don’t quite understand why the manufacturer positioned Thermalright AXP-140 as a solution for HTPC. The thing is that HTPS systems are never equipped with powerful CPUs. On the contrary, the users tend to use power-efficient processors (E5200/7200), so they will hardly ever need a very efficient cooling solution. Moreover, despite its modest height, AXP-140 is pretty wide and long, so it may not even fit into n HTC system. So, looks like this question remains open for now.
