Final words and conclusion
What to say at this point? Fractal Design has ... designed a beautiful looking, understated, near silent, and easy to install cooler that - to me - is a genuine breath of fresh air in 2017/18 (yes I'm well aware this unit has been out for a little while now). It has, in my opinion, very few vices. However, if you want a bigger and better summary... well, I guess we can break down the conclusion into a few separate parts. To me, that means quality/build, performance, installation, and - potentially - price vs. performance? Well, let's start?
However, before we go further, a small point. I am sure some are wondering what is the cause for the relatively small (4 degrees at most) change in thermals when comparing the automatic/stock configuration, and this initially confused me. However, I eventually figured out why. It turns out that this is a combination of AMD's XFR (i.e. the CPU boosting higher with sufficient thermal/power headroom) and the MSI B350M Mortar Arctic's automatic VCore being relatively heavy-handed, pushing up to 1.45v (though that would be in short bursts, though you can see this in screenshots), and sustaining the VCore at around 1.25-1.26. When you consider that the voltage increase from this value was fairly small, just 0.05v, the small delta begins to make more sense. Being fair to MSI, this is not behavior that is unique to this board. Other B350 and X370 boards I have owned have also been equally potent with VCore in 'auto' mode.
Quality and Use
Fractal Design has never - to my mind - released a poorly built product. This is to their credit, and this philosophy carries on over to the S24. Whilst the packaging and unboxing experience is fairly parred for the course for an AIO, the overall solidity and feel of the unit is something very nice indeed. Even down to the Fractal Design banding on the radiator fittings. There are some really nice touches, here, and they're appreciated. I have made my feelings clear toward the inclusion of an integrated fan hub, and I like this approach of reducing additional software/control suites as much as possible. Naturally, if you want to PWM control your unit, you'll either need to use a suite anyway or use the BIOS. Either way, the fact you don't need one in order to just use the S24 'as is' is excellent. Using the S24, therefore, really couldn't be any easier. In fact, I have no gripes whatsoever as regards either the build quality or using of the unit. A very strong start, indeed. Let's move on.
To be fair, the installation of these coolers is very similar across the board for all mainstream CPU sockets. It would seem that years of refining the AIO formula across the industry has allowed us to reach a state of affairs where it's nearly second nature. In fact, the only thing I needed to refer to the manual for was which nuts to use for AM4. The rest was self-explanatory. I appreciate that this will likely not be the case for a first time builder, but the excellent included manual and individually wrapped installation gear make this very easy indeed. A good 50% of the install, save for mounting the fans and radiator, can be done entirely tool free. I simply hand tightened the four threads to lock the block onto the CPU, and it wasn't going anywhere. In fact, the bolts have a very definite 'endpoint,' where you cannot tighten them more, even with a tool. The cooler also happens to be relatively compact, with 400mm hoses being entirely adequate in terms of length, but not excessive to the point where it can prevent your case from closing (yes, I have had that before, albeit in a very compact tower). Again, no complaints whatsoever here. Staying strong.
This might well be the polarising paragraph, depending on how you view AIOs vs. their air-cooled cousins. Some see AIOs as the 'ultimate' in cooling, and the fact that this lost to a 120mm dual fan air cooler - though it is from the kings of air coolers themselves - might be an immediate 'no thanks' to some. Consider the following, however. First, Fractal have 100% targeted the noise obsessives with this cooler. The fact that it stayed quieter when submitted to an overclocked chip than the Noctua did when at stock is truly impressive, I have to say. In fact, 34 decibels was barely above my room's ambient noise level of around 32-33dBa. The second point ties into the first, and hear me out.
The difference here was about 3 degrees, and whilst there will be more of a delta with a bigger air cooler, remember that the S24 was left at 'Auto' mode. Temps could certainly be dropped notably by just increasing fan speed using PWM mode. The second thing to remember is that if you're legitimately concerned that a matter of 3C will be the difference between a chip that is 'ok' and one that is too hot, chances are your overclock is too aggressive anyway. Turn it down. I hope you can follow my train of thought here, but I feel a though the very small temperature compromise is a very little price to pay when you look at just how much noise you 'save', for lack of a better term. Naturally, this delta will increase as you use beefier and beefier air coolers, but then you begin to run into space/size restrictions that just do not affect AIOs, especially those on the smaller end of the scale (i.e. 240mm or below). The performance could be better, but that point is just that. It 'could' be, but for the sake of acoustics, the automatic profile is kept so quiet as to be nearly inaudible, even when handling an overclocked 8 core chip. If you want more, PWM is there.
So this brings us to Price vs. Performance. Normally a term used for GPUs in terms of 'dollars per frame', it can also apply to cooling when you look at a relationship between the cost of a cooler and the temperatures that it delivers under CPU load. Doing a quick calculation, the Noctua unit is below 1 EUR (prices for both units taken from Amazon Germany) per 1 degree, whereas the S24 is up at 1.41 EUR per degree. On the surface of it, this is a bad result for the S24. However, we come back to the noise element. A difference of 5 dBa in a graph or calculation doesn't do justice to the perceived noise emitted by the cooler when under load.
What to say about this cooler that I haven't already covered? It now takes pride of place in my PC, replacing the NH-U12S. To be fair, this is more because I was getting a little tired of swapping coolers about. I would be happy with both. However, as a fair staunch advocate of air cooling, the ease of use/installation and overall performance vs. noise of the S24 impressed me enough to keep it for now. I, therefore, have no issue in awarding the S24 our 'Recommended' award, based on the above factors. It's a fairly simple conclusion, really. Do you want a performance/top flight (in terms of temps) unit? Buy something else. Are you silence obsessed? If so, I would urge you to consider this unit. I was continually surprised as to how quiet it stayed, even when cooling an overclocked 8 core CPU. Performance is fine, but that is not why you would look at the S24.