W A R N I N G !

W A R N I N G !

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Wednesday, July 27, 2011

NZXT Havik 140 CPU cooler - User review - Special pseudo-fanless edition

I never thought I would get my hands on an NZXT product. NZXT is famous for its chassis and case fans, typically aimed at the silent computing enthusiasts. I also am a silent computing enthusiast, but I never spend on expensive casings and fans. I have never spent on CPU heatsinks either since I got the Ninja in early 2006.

And it happened that I won a contest (or is it more of a lucky draw?) and got myself a NZXT Havik 140 CPU cooler. And being a number-hunter, I promptly proceeded to test it.

But, there are already multiple more-professionally-done reviews available on the web. So it goes against my principle to make another half-assed production of the same thing.

So, I'm making something else.

I'm going to get numbers. But the problem with numbers is, they don't mean anything if you don't understand what they mean.

...Sorry, that one applies more to audio, in most other fields people don't flak each other with illogical theories and meaningless numbers.

The problem with numbers is, they don't necessarily apply in other scenarios.

And my scenario is different.

I run my tower heatsink pseudo-fanless, with the rear exhaust casing fan acting like the CPU fan through a duct. The casing fan is plugged to the CPU fan header. Well, for a while I didn't use a duct, because the Ninja is so close to the exhaust and PSU. (But a duct still significantly improved temperatures, cool.)

Because the most effective way of making things quiet is to make less sound in the first place.

And to top it off, the exhaust has a top speed of 1100rpm and runs at 700-800rpm with motherboard fan control.

So the heatsink has to work with low airflow. And this is usually not tested in reviews. Even silentpcreview.com where people expect to find the quietest reviews does not usually test fanless or ducted conditions. This is understandable, because the fan is part of the whole heatsink product, the heatsink is usually not designed to operate without a fan (or with low airflow), and without the fan temperatures shoot skywards in the best of coolers and the CPU melts in the case of low-end coolers.

Before we start the testing, lets go for some customary photos.

The box, beside a WRT54G, for size comparison

The box

Still the box

The side of the box. At least the English has no grammar errors.

The two fans you first see when opening the box

Box contents

The heatsink itself

A 120mm fan to show the size. In Chinese, "say big not big, say small not small."

A splitter to control two fans using one CPU fan header. A nice touch.

The bracket installed. From here onwards no manual is needed, but up till this stage it was very confusing. The backplate had to be flipped the right way up depending on Intel or AMD, 4 things needed to be removed from the backplate and 4 insulating stickers pasted, 4 thumbscrews and 8 small normal screws screwed in pointing upwards with the Intel bracket below the AMD bracket. "Easy installation", yeah right.

The bracket is there for the cooler to be mounted facing two possible ways 90 degrees from each other. But at this point I noticed a potential problem - the length of the screws protruding from the metal plates are the same, resulting in different heights when two of the plates are mounted below the other two. This will result in different mounting pressures depending on which way the cooler is facing, or worse, which will be covered later.

Base is smooth to the touch, but won't be winning any prize visually.

Two ways it can be mounted,

like this

...or like this. The Ninja can be seen at the side. It is a novice, that is why it gets seen.

Comparison with the Ninja:

And now is the problem I mentioned earlier. In order to have the wide side facing the rear fan on most AMD motherboards, you have to use the screw with the lower height (if installed according to the instructions manual), and it is too difficult to press down the spring-loaded screws hard enough for them to reach. It may be possible with tools or just adequate grip, but you have to do this with the CPU cooler on the motherboard, which adds many levels to the difficulty.

A trick I used, instead of mounting the metal pieces I'm talking about below the other metal pieces, I mounted it above. I think the picture below shows better what I am talking about.

Compare it with this picture from above and spot the difference.

There are issues with this approach though. The heatsink pulls upwards, and while the original design have the metal pieces stopping each other, here only the screw threads of 8 small screws are preventing the cooler from coming off. Second, the mounting pressure may be reduced, but only if the screw cannot screw down to the same depth. So far, there has been no problem.

On retrospect, another way is to loosen the 4 thumbnuts connecting to the screw for the backplate, enough for the spring-loaded screws on the heatsink to reach, then tighten the thumbnuts, then tighten the screws.

I could reuse some of the pieces of the Ninja's duct.

Another view

A photo to show the proximity of the heatsink to the PSU. Adding a wall here to force air through the dense fins may cause too much resistance and make the PSU noisy, so I left it like that.

And now, the important part - the numbers

Unfortunately there was some problem with measuring room and ambient (in chassis) temperature. However, just with idle and load temperatures the performance of the cooler can be guessed, by temperature difference due to power difference.

This is the system power when idle (800MHz @ 0.75V)

And this is Linpack @ 2.8GHz when overvolted to 1.55V.

216 - 74 = 142. The efficiency of the 80 Plus Bronze PSU at 216W input power should be around 85%, considering it is a lower-power version of the 750W version and I am on 230V. This gives 184W of DC power.

At 74W, efficiency is maybe 78% (guesstimate), giving us 58W of DC power.

And 184 - 58 = 126. Well, there are VRM losses too and other parts like northbridge and RAM, but 100W should be a fair estimate. This is the CPU's power difference between idle and Linpack.

Notice I keep saying Linpack instead of load. Because Linpack makes your CPU hotter than most other loads including Prime95 and OCCT (non-Linpack test; I use the Linpack test inside the OCCT software package).

To get the thermal resistance of the cooler in °C/W, simply take temperature difference between idle and load and divide it by power difference of the CPU between idle and load. In this case, 100W.

With both the Ninja and Havik, I got around 31°C idling.

With the Ninja, I got around 67°C under Linpack. With the Havik, I got about 68°C. Fan is at full speed of 1100rpm.

The Havik lost to the Ninja by an inconsequential one degree, which is well within the margin of error. A degree may mean a lot in other scenarios, but not when you have a 100W heat source raising temperatures by 37 degrees. In such scenarios, a small difference in performance is all needed to generate a few degrees of difference.

Calculating, that gives us 0.36°C/W and 0.37°C/W for thermal resistances.

0.37°C/W is not bad; it is sufficient in most cases, that includes a Phenom II X3 720 at 1.55V doing Linpack. While the best oversized heatsinks today have performances of 0.10+°C/W or even less, we are doing it pseudo-fanless.

So, the Havik did not beat the Ninja, despite being newer and more expensive. But -

1) It was further away from the exhaust fan
2) It does not have as much horizontal depth
3) Its fins are more densely packed
4) It comes with two good fans which I did not use

Furthermore, the Ninja's wide fin spacing design is known to be better for low airflow and worse for high airflow, relatively speaking. So the Havik matching the Ninja in low-airflow condition is a feat, because the Havik is definitely the better performer with fans attached. Then again, most high-end coolers are better than the Ninja with fans attached.

But the Havik was disadvantaged. So I redid the duct and redid the test.

I know a good friend called paper.

With the duct v2 in place, the tables turned with the Havik one degree better than the Ninja at 66°C for a thermal resistance of 0.35°C/W.

Which is still an inconsequential difference.

With more creative ducting, particularly making better use of the PSU fan, I am positive temperatures can get even better.

So, lets summarize this thing.

The Good:
Excellent pseudo-fanless performance
I can guess it has excellent fanned performance too
Relatively small (slim)
Comes with two good fans

The Bad:
AMD installation has some issues (Intel's look straightforward though)
Not as cost-efficient as some other coolers. But hey, the size, is small, and did I mention the fans?

The Ugly:
My casing's side panel can't close with it installed.

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