Great review.

Since mounting contact is such a critical aspect of heatsink performance, I was wondering if you'd able to give it a wishy-washy rating (say 1-10). I'm curious what the weight/mounting quality/performance correlation would look like. My gut feeling tells me it will be quite strong, unless there's a major flaw in the design.

Good to see another well-performing compact heatsink.

I wouldn't start separately rating the mounting, as it gets rated as part of the efficiency already (poor mounting, poor efficiency), but it is a critical aspect.

Is there a single Noctua fan whose specifications aren't an explicit lie? I've been through all the Noctua reviews on this site and not one has matched up against their so-called 'specs.' Even funnier, the fan is beaten by a fair margin at the ~12dB level by the Nexus, despite it being about one-third of the cost. Noctua's fan ratings are truly a marvel of German 'engineering'

I also had a good chuckle about the newest NB fan, which rattled off a slew of impressive traits, like 'world's best fan', 'first bionic fan', 'funded by the minister of blah blah', only to get beaten by an aged Japanese fan without all the boisterous bullshit.

I have no special love for Noctua (defending a company is wasting one's breath), but the bashing is getting tiresome.

The fan specs not matching has been discussed many times. Different specs result from different measurements, it's subjective data since there is no well-adopted standard. Products getting slapped with marketing bs is just how it is. Oh, and Noctua is Austrian - not the first time a spiteful person has confused the two countries.

So why all the hate, Koldun?

Because their fan specs are obviously exaggerated to make themselves look better than they are, as opposed to having some super precise measurement system that only they are privy to.

This all sounds quite negative. Have you got any experience with Noctua yourself? I'm basically with Das_Saunamies on this - note that they're Austrian not German, noctua.at kind of tells you this.

As Das_Saunamies alluded to, they may have put their sound-meter at 2 meters distance and didn't follow ISO-Blah. And even if you knew their dB(A) values followed a certain norm, the bearing could still reproducibly growl like an airplane and you would be non-the-wiser from the dB(A) figure. That's why you read the tests here.

Noctua has very clever marketing and built a perceived high-quality brand, just like Apple, BMW or Mercedes. There are many cheaper equally well performing alternatives out there.

Good to see review of this very interesting heatsink.

Though what this review misses is comparison to NH-U12P.
Would have been real interesting to see how one additional heatpipe fares againts possibly increased airflow impedance.
In this user made comparison U12S wins when using Noctua's fan and 1850rpm Gentle Typhoon at full speed.

I think this point is good to bring up again. With these performance figures, it makes little sense to put these heatsinks in together with the really compact ones - "these" being the Noctua NH models, both of which get closer to 30 °C compared to the over-40 and over-50 of the compact heatsinks.

Any chance of a rematch with the Big Boys? And if not... how much?

Looks like the new SecuFirm2 mounting system is a step backward from the NH-U12P SE2 SecuFirm and the HSF is more expensive as the NH-U12P SE2 can be had for $43 CAD. NH-12S is pretty disppointing and dropping the 775, 1366 support is silly. The only improvement is the PWM fan you get with the cooler over all. Seems Noctua is going backward in quality, this really lacking compared to the D14 and NH-U12P SE2.

Eh ? NH-U12P SE2 uses SecuFirm2 too.

There are actually three different versions of SecuFirm2. The one fitted to the NH-U12S is the 1150/5/6 compatible simplified version which Noctua designate as NM-i115x. The original SecuFirm2 remains as the NM-I3 which fits 775, 1150/5/6 and 1366. The third SecuFirm2 is the NM-I2011 for the Sandy Bridge-E 2011 socket. All of these variants should be available as separate kits through retailers, for example a search on Amazon.com should find all three for around $10. However as the 775 and 1366 sockets are obsolete the continued availability of the NM-I3 is probably questionable, so if you want one the clock is ticking.

LGA775 was basically completely obsolete already two years ago and similarly Sandy Bridge E also made LGA1366 and its Nehalems old tech.
So nitpicking on dropping support of these ancient sockets just shows lack of better arguments.

And that comes from someone who's using LGA775 platform, Q9550 E0 undervolted to 1.2V and overclocked to 3.7GHz. So don't think on blaming me being someone who's constantly buying the newest components.

The whole shifting around of mounting holes is annoying. Just get an ATX standard and be done with it. If PCB designers can cope with new sockets, I'm sure they can cope with constant holes. Damn you planned obsolescence!

I'll be interested to hear what the review team think of the U12S's big brother, the U14S. I have just used one in a Haswell build, and I ended up choosing to mount it 90 degrees from the usual orientation because I was concerned about it overlapping the first PCIe slot on a MicroATX board. It is blowing upwards (not a bad thing), and I opened the ceiling vent in a Fractal Design Define Mini to give the hot air a suitable path (I'm not usually a fan of ventilation in the top of the case, but it may be the best solution here.

I've used a variety of Noctua coolers over the years (the D14 is a favourite), and I have to agree with the comments that one of Noctua's big advantages is availability I can get Noctua coolers anywhere, but many of the other good ones are only available online.

The hole position for LGA 115x has been constant for quite some time, surviving the 1156, 1155, 1150 sockets. I'm sure that's no accident.

Those holes don't suit LGA 2011, but fair enough - it's a significantly bigger socket. As I understand it, the Ivy Bridge E CPUs are expected to use LGA 2011 as well.

More annoying to me is motherboard designers who put stuff on the back of the motherboard in the area that the Noctua backplate covers - there are a number of Gigabyte motherboards I won't use for that reason, and one ASUS, too. I had to use an L9i for a mini-ITX build because the L12 backplate would have been on top of some components: voltage regulators and other surface-mount components (capacitors? resistors? - who can tell when they are surface-mount?)

This is something I haven't run into yet, but can see how it would be an issue - it's annoying enough when it happens with video or other add-on cards, which is a serious consideration in compact builds. I hope the backside-component trend goes away, or they at least recognise users need that space.

I am trying to compare results from these two reviews:
http://www.silentpcreview.com/article1343-page1.html
http://www.silentpcreview.com/article1359-page1.html
and it seems that the smaller cooler (U12S) is more quiet with the stock fan, and not really far behind in terms of cooling - being even better if looking at results with single stock fan (page 6 of both reviews).

I doubt it can be true, but perhaps someone can explain the differences to me?
I am wondering which one should I buy to a silent home rig...

The differences in the degree/decibel tables are probably from two different test rigs. The "small" coolers take on the 1155 platform and the "large" ones the 1366, i.e. a 95 W TDP CPU or a 130 W TDP CPU. This brings us to the big question: what are You cooling?

Unless it's some crazy overclocked monstrosity from yesteryear, I doubt either cooler would have trouble keeping the CPU cool and the fan RPM low. What you really want to check out in this case are the verdicts on the coolers' stock fans, in case you're not interested in swapping out for a personal favourite or an all-round champion. What caught my attention in the fan verdicts were these two tidbits:

and

To summarise, the 120 mm version seems to have died out, and probably for a good reason (+1 for the 140 mm). The 140 mm does have its quirks, but seeing as you're going silent, your RPM will be low and the character most likely not a problem (+1 for the 140 mm). HOWEVER, the 140 mm is probably more expensive, and it is naturally larger and heavier (+2 for the 120 mm).

My opinion: go for the 140 mm if you can afford it, it fits into your setup (case, mobo, RAM), and the heavier weight is not an issue. We'll see if it's pure overkill when we hear what your setup is, though.

I've recently helped build two mITX rigs with the 120 mm version and no complaints so far, but I haven't heard either one live myself.

Thank you for an excellent answer - I am getting closer to a final decision

I will be cooling a Pentium G3420 on a MSI B85-G43, with high probability of changing the CPU to Core i5-4570 or similar in a year or so (I have added this info in my footer now)...
I do not overclock and rarely play games, the computer is used mainly for photo editing, and so the silence takes priority over computing power.
The case is an old Chieftec DX01 medium tower, so plenty of space for any cooler lower than 170mm.

The price difference is not an issue foir me as long as I would not be spending too much money on things I would not ever not need (OK, I do it, but in a separate field ).

Happy to help.

The Pentium CPU you have now has a TDP of 35 W, and you can get a 35 W TDP version of the i5-4570 (it's the T, http://ark.intel.com/products/75045/Intel-Core-i5-4570T-Processor-4M-Cache-up-to-3_60-GHz). Both can definitely be handled by either heatsink.

My i5-3570K has a TDP of 77 W and the ol' U12P handles it just fine. I replaced the Noctua fan(s) with a Scythe one for extra quiet, as Noctua fans have tended to work better as case fans for me. When I stop the GPU cooler's fan the rig sounds like a whisper.

I know photo editing is heavy on writes, but I don't know about CPU heat. Could look into some massive heatsinks like the Macho or Mugen for passive or semipassive cooling, I reckon.

PS. Forgot to specify my use: regular gaming, semi-heavy professional software, but nothing that would tax the CPU to the absolute limit. The idle & load data in my sig is from testing, not use, so it describes a maximum use scenario of sorts.

Yeah, this CPU is definitely not very demanding...

I'd go with U14S, hopefully it will be more 'futureproof' - and I prefer one slow barely audible fan that can increase RPM when needed than a totally passive solution...

Thanks a lot for the help again!