be quiet! Pure Rock Review

The company known as be quiet! produces quite a range of products. Today we are looking at a cooler called the Pure Rock. It is a four-heatpipe heatsink, rated at 130 Watts. Now, that’s a lot of cooling for a four heatpipe heatsink. Will it do that well? With only four heatpipes? Let’s find out.

Introduction

As the “about us” section of their website tells us, be quiet! is a trademark of Listan GmbH & Co. KG. They produce equipment focused on quiet performance, whether it is power supply units or heatsinks, cases or fans, windowed side panels or individually sleeved power cables in multiple types and lengths. They make Thermal Interface Material — TIM, also known as “thermal grease” — and silencing mats. As I said, lots of stuff. We have previously seen their Silent Base 800 in a review here at Overclockers.

Features of the Pure Rock (from the be quiet! product page):

Quiet and Effective Cooling

High cooling efficiency

Silence-optimized be quiet! fan with PWM function for best balance of cooling and quietness (max. 26.8dB(A))

Assembly from atop the mainboard possible

Four high-performance 6mm heat pipes with aluminum caps and cover

Compact single tower design

In a thorough-going German manner, we have Specifications,
courtesy of a be quiet! “listing-overview” (a spreadsheet):

The fan is a Pure Wings 2, model BQ PUW2-12025-MS-PWM.

Packaging and Parts

The Pure Rock comes in a cardboard box that has been printed black, with white and light print, with a picture of the heatsink on the front. There is a diagram and a table of specifications on the back.

Inside, the heatsink is protected by being suspended in cardboard. That means you can recycle the entirety of the packaging, but pulling out the heatsink is tricky.

The heatsink comes with a large number of small parts. They are sitting on the manual so you can see what the manual looks like. You can also download the manual here. The small parts that come with the Pure Rock include an LGA 775 backside spacer, two fan clips, four LGA 2011 spacer-screws. A backplate, four LGA 115x spacer-nuts, a mounting bridge, various screws, O-rings, two AMD brackets, two mounting brackets, and a fan.

Pure Rock Mount

be quiet! was not entirely original with how they put a Pure Rock on a motherboard. It has strong resemblance to the excellent Prolimatech mount. If you are going to imitate something, imitate the best. Here, be quiet! did a wonderful job of coming very close to the Prolimatech mount. One can speculate here on how they handled the intellectual property, but you will mostly like what they did.

We will start here with O-rings. The left picture shows how the O-rings fit over the backplate screws of the Pure Rock system. The right picture shows the completed backplate assembly.

Here we have a piece of cardboard standing in for the motherboard. On the Pure Rock, the spacer-nuts screw down over the backplate screws.

In the Pure Rock system, flat headed screws hold the brackets down on the spacer-nuts. The mounting bracket is bent, to provide a centering mechanism for the mounting bar — be quiet! calls it a “mounting bridge.”

In the left picture, the Pure Rock’s mounting bridge is upside-down. The exposed underside shows the side walls on the ends that keep the bar centered on top of the raised portion of the brackets. In the center of the mounting bar are the transverse ridges the hold the heatsink in place. You can also see the “mounting bridge fastening screws.” Note that these screws do not have springs. The mounting pressure is provided solely by torsion on the mounting brackets.

The right picture shows the Pure Rock’s finished mount. You can see how the sidewalls at the ends of the mounting bar surround the bend in the mounting bracket, centering it.

You can see for yourself how much or how little the Pure Rock System resembles the Prolimatech. Given the Prolimatech mount has been unchanged since it was changed slightly 2010 (thus assuring mutual compatibility among the company’s heatsinks) and the Pure Rock system is from 2015, you can decide for yourself whether the Pure Rock system has benefited from the five years that have passed.

Pure Rock Closeup

Let us take an airflow-oriented view of the Pure Rock. You can see how fat the fins are — not thick, but not terribly thin. They are spaced well enough that a relatively gentle fan will produce significant airflow through the device. Look carefully at the aluminum surrounding the heatpipes. You can see a little copper there. Obviously the aluminum does not take up the full width between the fins.

In the right picture we have an oblique view that shows the slot for the mounting bar. This slot will keep it centered, side-to-side. The ridges on the underside of the bar fit into grooves in the slot, fixing its long-wise position on the heatsink.

A top-down picture of the Pure Rock shows that the makers intend to keep it neat. Notice that the heatsink ends are capped. You can see how the fan clips fit onto the fin stack. But the pretty top obscures your view of the fin stack.

A bottom view of the Pure Rock shows us several things. First of all, it shows the plastic contact surface cover and the pre-applied TIM. Note that the TIM is already smeared. That came when the heatsink was pulled from its box and the protective cover fell away, failing to protect the TIM. Next we see that the Pure Rock indeed has four heatpipes. Finally, we see that the fin stack is deeply grooved. Since this is a symmetrical heatsink, the other side is just the same.

The left picture shows us the bottom without its cover. You can see some of the damage the TIM took, but does that contact surface look flat to you? The contact block looks to be two pieces here. Were the heatpipes soldered into the black or clamped? Down at the finstack level, you can see just how deeply the grooves go into the stack.

The right picture shows a closeup of the fins gripping the heatpipes. Again, a little copper shows but it’s mostly aluminum here.

Here is the included fan clipped to the Pure Rock. See the table above for its specs. In the next picture, you can see the backplate mounted on a motherboard.

In the first picture, we can see the Pure Rock battened down, ready for action. This picture is actually from the test system, so the heatsink really is going to start cooling soon. Note that this picture is aligned with the mounting bar, what be quiet! calls a “mounting bridge.”

The next picture shows the mounting bar transversely. We can see that the mounting bar just about butts up against the VRM heatsink of the motherboard. Luckily the mounting screw is in a hole, not a slot, or getting it on correctly would be a major pain. You also get a good view of the mounting brackets and the spacers. Note that the RAM is populating only the first and third memory slots here.

A top view of the Pure Rock gives an excellent look at how the pieces of the mounting system fit together.

The side view shows that the fan – a standard 25 mm thick fan – sits over the top of the fourth memory slot. That means that either you stick to two RAM sticks, or you use low-profile RAM, which will slide in under that fan. I strongly advocate Ultra Low Profile RAM. You can see that I paid for some.

One more thing to notice: those fan clips. They fall off the fans easily enough, but once they are on the fin stack, they hold firmly. Also, when you need to adjust the fan’s position (perhaps you mounted it crooked) you just pull the handles. That makes these fans easy to mount and easy to adjust.

Here is a picture of the contact surface of the Pure Rock. Obviously the picture was taken after the first cooling runs of the heatsink, so the bottom shows a bit of wear. As you can see from the reflection, the surface is not exactly a perfect mirror. Further, I did my rocking razor blade test to ferret out any curvature. This is a very sensitive test. I can pick up convexity that won’t show in a picture. In this case, the heatsink base was flat, so I have no problem remounting it and testing it again. That’s a good thing, as you will learn in the testing setup section.

Testing Setup

The Pure Rock came from be quiet! The NH-D15 came from Noctua, and the Prolimatech Megahalems was purchased retail at the end of 2009. Each heatsink was mounted on the night before testing. This gave the TIM most of a day to do any migrating it was going to do.

Linpack runs in surges. When the temperature is graphed, you see ragged plateaus. In looking for cooling solutions, you want to know how well a heatsink cools those plateaus. So at 4.5 GHz the temps under 70 °C (the valleys) were ignored in analyzing core temps. At 4.4 GHz the temps under 60 °C were ignored.

Each test run was 30 minutes in duration. The last 20 minutes of each run was measured, and the core temperature logs were analyzed in Open Office spreadsheets. An Intel chip reports its temps in one degree increments, so for best accuracy these reports should be averaged in aggregate. Here the core temps were measured once a second, resulting in 1200-line spreadsheets.

The digital thermometer measuring air temp reported its measurements in increments of 0.1 °C. The ambient temperature was measured every five seconds, resulting in 240-line spreadsheets. The mean ambient temp was subtracted from the mean core temps, resulting in a net temp for each run. Finally, the three net temps were averaged.

The Sound Pressure level was measured 1 meter from the heatsink, with the motherboard set vertically, the way it would be in your case. The ambient noise for this testing was 31 dBA. So the net SPL is the sound pressure level measured at 1 meter, less 31 dBA.

The testing for the Pure Rock ran into a snag when the pre-applied TIM needed to be re-applied. That and the death of a CPU shoved this review to the back burner. Then be quiet! sent another heatsink for review (upcoming). That one came with a tube of be quiet’s TIM, so this review could go forward.

One of the problems with a four-heatpipe cooler is that it is physically impossible for it to keep up with decent six-heatpipe heatsinks. During preliminary testing the Pure Rock never made it past ten minutes at 4.5 GHz, where I test six-heatpipe heatsinks. So I tested it at 4.4GHz and a lower Vcore. But that left an issue: what to compare it with? This is the only 4-pipe heatsink I have. In the end, I picked two 6-pipe heatsinks and ran them at 4.4 GHz, comparing them to the Pure Rock.

Results of Testing

Let us look at the performance of the three heatsinks at 4.4 GHz. As expected, the 6-heatpipe heatsinks did a great job of keeping this system cool. The Pure Rock is not in the same league as those coolers. Even at 4.4 GHz, during two of the three runs, the max temp of the Pure Rock was 97 °C. One more degree at Real Temp would have logged it. The third run maxed out at 96 °C, so at no time did we have cool cores. What this tells us is that even at 4.4 GHz, keeping the system from throttling was barely within the capacity of this 4-heatpipe heatsink. But note that it did the job.

Now be quiet! advertises on the box that this heatsink has a TDP (Total Design Power) of 130 Watts. According to the Intel Gadget that I use to keep track of this, the test runs averaged 127 Watts, with lots of 131 and 132+ entries. So, given a flat plate heater, this heatsink will most likely keep a 130 Watt heat source under 100 °C.

Conclusions

The Pure Rock kept a lightly overclocked Devil’s Canyon i7 4790K system from throttling. Quite an achievement. No, this heatsink is not ready for the major leagues, but you knew that. With only four heatpipes, it cannot cool as well as most of the six-heatpipe heatsinks can do. Further, few people crank up Linpack with AVX2 for extended runs. So for normal use, the Pure Rock is more than adequate.

We looked hard at the mount, and compared it to a known good one. The Pure Rock’s mount looks very good, right up there with the older mount. In some ways it was better – better centering on the mounting bar, for example. In one respect, it wasn’t as good – it used torsion rather than spring-loaded screws to apply the mounting pressure for the heatsink. But that decision kept the cost down, and low cost is crucial for this heatsink.

This heatsink is a breeze to mount. Easy. Combine that with the fact that the contact surface was flat and it doesn’t matter that the Pure Rock used torsion instead of spring-loaded screws. It is welcome on my rig any time.

Availability

This heatsink is be quiet’s budget offering. It is available through Newegg for $34.90, with free shipping. In Europe the MSRP is 37 Euro. That makes it a stellar performer for the price.

Pure Rock Pros

• It really does cool 130 Watts
• Flat Contact Surface
• Easy Mount
• Manual is clear and is available online
• Relatively Quiet
• Fan clips make it easy to adjust fan position

Pure Rock Cautions

• Uses torsion mount instead of spring-loaded tension screws
• Four heatpipes in line with its low price

Pure Rock Cons

• none

Click the stamp for an explanation of what this means.

Ed Hume (ehume)