Matching CPU to Heatsink Cooler: Does It Matter?

By Tom Jaskulka

Back when I was given an opportunity to review SilverStone’s new Argon series of coolers, the system I was using at the time for testing CPU coolers was based on an AM3+ processor. The AR03 was recommended out of the two for my platform, due to it’s larger physical size than a Socket 1155 CPU – for which the smaller AR01 would be more appropriate.

This generated some questions for me – exactly how much of a difference does this make? How important is it to pick an appropriate cooler for your platform, and what exactly does that even mean? Ultimately they’re all just a chunk of metal that transfers some heat, right? I took the opportunity to compare the AR01 and AR03 Argon coolers from SilverStone on two different platforms to see some data. I had a theory, now it’s time to put it to the test!

I don’t foresee any fundamental scientific discoveries here (a lot of the following information will fall under the “common sense” category), but I was curious what the difference between these two coolers would be on different-sized CPUs. What follows is a short summary of what I found!

Features & Specifications

The Question

This won’t be a full product review of either cooler, and I’m going to assume that you’ve read the SilverStone Argon AR01 and AR03 product reviews. If you haven’t, feel free to do so as those articles will explain in detail the CPU cooling testing procedures we use at Benchmark Reviews. Keep in mind this article uses two different platforms though, so there are a few more variables to potentially get in the way – while the results may not be scientifically exact, I bet there’ll be enough of a trend to possibly draw some conclusions. With that said, just what ARE we looking at here?

Well, SilverStone has a total of three coolers in the Argon line – the 120mm 3-heatpipe AR01, 92mm 3-heatpipe AR02, and 120mm 6-heatpipe AR03. Each of those coolers are designed for a different purpose, and are tweaked to address different parts of the cooling market. The smallest AR02 cooler is for space-constrained systems. The 120mm AR01 appears to be a direct competitor for Cooler Master’s popular Hyper 212 cooler, and the larger AR03 adds even more size and performance to complete the lineup.

The cooler that really spawned all of these questions is the Argon AR03. Since it is the larger of the two heatsinks with six direct-touch heatpipes instead of three like the AR01, the base is correspondingly larger to accommodate them. As you can see in the picture above featuring the AR03 and a Core i5 2500K processor (Socket 1155 / Sandy Bridge), only four of the six heatpipes actually touch the heat spreader of the processor.

Compare that to the thermal paste imprint of an FX-8320 CPU (Socket AM3+) and you can see the heat spreader on this processor is covered entirely by all of the heatpipes on the AR03. That’s the same heatsink with two different CPUs. Just by looking at the pictures, could we assume we’re leaving some performance on the table? Are those two untouched heatpipes useless on the smaller CPU?

Enter the AR01. Designed for smaller and more mainstream CPUs with less cooling requirements, the base of the AR01 has the opposite problem. It covers the smaller socket 1155 CPU almost perfectly, but leaves some of the larger FX CPU’s heat spreader uncovered. You can see in the photo above there is some space remaining on the sides of the heatspreader that is untouched by thermal paste (even after being smeared around a bit while mounting/removing the heatsink). Look for the lines caused by the edges of the heatpipes – this is essentially the “useful coverage area.” The smaller Argon AR01 cooler uses only three heatpipes, but they are eight millimeters wide (compared to the six 6mm pipes on the AR03).

Above you can see how the AR01 fits on Intel’s mainstream socket vs. AMD’s AM3+ FX CPU. It’s tough to tell on the Intel CPU because of the perspective, but those heatpipes barely cover the heatspreader – on the FX CPU, there’s a few millimeters on each side that are covered by the base (but not the heatpipes themselves).

Some really simple rough math gives us 24mm of contact surface for each cooler on the 1155 socket CPU (that’s 4 pipes touching x 6mm for the AR03, 3 pipes touching x 8mm for the AR01). If everything else were equal (which they aren’t, but let’s simplify this a bit) could we assume the cooling capabilities of 24mm of heatpipes are going to end up the same on smaller sockets? Let me rephrase that to be a little more consumer-relevant: Is there a point to buy the AR03 if you have a smaller CPU, or will the AR01 perform the same on those smaller sockets?

We’ve already seen how each cooler performs on the overclocked AM3+ testbed, so let’s see how they compare on a smaller CPU.

Testing & Results

Testing Methodology

You can refer to the Argon cooler articles for more extensive details on how they were tested with the FX-8320 CPU. For getting temperatures from the Core i5-2500K, the process was pretty similar (although it goes without saying different components were involved). AIDA64’s built in stress test was utilized for both CPUs – once temperatures “plateaued”, peak temperatures were recorded and the ambient temperature was subtracted to arrive at a change in temperature (that you see in the chart below).

Test System

• Motherboard: ASRock Z68 Extreme3 Gen3
• System Memory: 8GB Crucial LP DDR3 1866 MHz
• Processor: Intel Core i5 2500K
• Audio: Asus Xonar DG
• Video: Sapphire AMD Radeon 7970 3GB
• Disk Drive 1: Western Digital Black 1TB 7200 RPM 3.5″ HDD
• Disk Drive 2: OCZ Vertex 2 50GB SSD (Used as SRT Cache)
• Enclosure: NZXT Phantom 820
• PSU: Fractal Design Integra R2 750W
• Monitor: Hanns G 27″ 1920×1200 LCD
• Operating System: Windows 7 Ultimate 64-bit

Results

On the overclocked FX processor (consuming about 200W) we saw a pretty large disparity between the AR01 and larger AR03. Obviously, larger processors like the FX series and socket LGA 1366/2011 processors are the intended application for the AR03, but what about smaller CPUs like the Sandy/Ivy Bridge Core series? Are the two untouched heat pipes on the larger AR03 “wasted?”

I guess that depends on your definition of waste. The benefits of the larger AR03 are obvious on the larger FX CPU’s heat spreader (and increased thermal output), but you don’t really lose performance if you move the AR03 to a smaller CPU. Adjusting for ambient temperatures, the AR03 performs almost exactly the same, even with two heatpipes “wasted.”

In fact, it looks like my math wasn’t too far off. Looking at the i5-2500K result specifically, 24mm of heatpipes look like they perform very similar – regardless of how they’re packaged.

CPU Cooler Conclusion

All of this is just a way to say the obvious – a greater amount of contact surface area generally transfers a greater amount of heat. One could infer then, that a similar amount of contact surface area transfers a similar amount of heat, despite the platform. When choosing a cooler for your CPU though, contact pressure and surface area are probably the greatest factors for the ability of the heatsink to conduct heat. None of this is really new ground (as later uncovered by Olin Coles during an extensive thermal paste review) – many of these patterns have revealed themselves over the years that Benchmark Reviews has analyzed CPU coolers.

I have to wonder though, will all of these “truths” about CPU coolers slowly become irrelevant? As the physics of ever shrinking processors changes (and the nature of their heat output with it – one of the reasons I still like my i5-2500K over my i5-3570K) will we run out of space for any number of heatpipes? Cooler Master has notably experimented with vapor chambers on some of their CPU coolers – would technologies like this become necessary to extract heat from smaller and smaller CPU dies? The results haven’t always been promising, but perhaps it would fare better on a ultra-modern platform (would the faster heat-spikes of Haswell be tamed by such features)?

For now, when it comes down to it, choosing a CPU cooler might be as simple now as picking a price point – if there’s any pattern I’ve discovered, it’s generally “you get what you pay for.” I would assume manufacturers of higher-end CPU coolers end up testing these products far more in depth than I could at home. Of course, we’re always willing to test those manufacturer claims to make sure you’re getting your money’s worth – that’s why sites like ours exist! SilverStone was right in recommending the larger AR03 for an overclocked FX-8320 processor, but even on smaller CPUs the AR03 saw a little performance improvement (it just wasn’t as necessary on the smaller i5-2500K processor).

So does any of this matter when choosing a CPU cooler for your CPU? While there are many variables still to discuss, I’m not sure I could say you could pick a “wrong” cooler – they all cool better than the stock heatsink! Obviously there are coolers that are more appropriate for certain applications, but since the latest CPUs seem to be limited by their manufacturing process anyway you can generally let your budget and aesthetic tastes decide.