An AIO liquid cooler with an expandable waistline
Swedish chassis mafia Fractal Design is well known for its range of PC cases, but now it’s got a range of AIO liquid CPU coolers too. ‘Range’, however, may be a bit too grand a word to use for just three products. Whatever, Fractal has called on the expertise of Alphacool, a company that knows a thing or two about liquid cooling. The dual-fanned Kelvin S24 is the middle cooler in the setup, sitting between the single fan T12 (120mm radiator for £75) and the triple-fanned S36 (360mm radiator for a princely £105).
Although the entire Kelvin set comes as all-in-one kits, they’re really more like hybrids between an AIO and a DIY design. They’ve been created to be expandable, not expendable, so it’s possible to add another CPU block or a GPU block if so desired. Fractal has fitted the pump and radiator with standard G quarter-inch threads, making this job even easier as it opens up the options available to expand the system. The pump is also designed to be topped up if need be with a fill port fitted on one side for this very purpose.
The S24 has been ambitiously Fractaldesigned to handle up to two CPUs and one or two GPUs. The water block and pump unit is quite compact at 69 x 69 x 40mm and said pump has a ceramic bearing and runs at 2,400rpm. That produces a water flow of 72l/hr and has Dry Run Protection designed into it so it can still run without damaging itself should the system run out of water, though the same may not be true for your silicon. Especially if it’s started gasping for the wet stuff thanks to an errant untightened bolt.
Two 320mm long tubes run from the block to the 275mm radiator, and have anti-kink coils fitted to them. Both the cooler block and radiator are made from pure copper. Keeping everything cool is a pair of Fractal’s own Silent Series 120mm fans which are PWM controlled with a decent spin range of 800 to 1,700rpm.
Fitting the S24 is straightforward thanks to yet another superb Fractal manual which shows all the steps with highlighted diagrams. We did have a bit of niggle joining the two halves of the mounting bracket together, but it may have just been our unit. Once they’re together though there’s no getting them apart without resorting to some serious tools. But despite that, the rest of the fitting is super simple.
The pump fixes to the backplate via four thumbscrews which use springs to prevent over-tightening. The longest job is screwing in the eight Hex screws which fix the two fans to the radiator. It may seem annoying for Fractal to use Hex instead of normal screws, but thankfully a Hex key is in the parts bundle. Woe betide anyone who dares lose their Hex however.
The S24 performed well in testing and kept our i7-4770K at just 17°C while idling with no real noticeable noise coming from either the pump or the fans. With the processor loaded to 100 per cent, the fans still remained very quiet and the cooler kept the CPU at a very reasonable 49°C. Even when overclocked to 4.5GHz the fans remained quiet at idling with the temperature of the CPU at 21°C. However, loading the CPU to max in its overclocked state meant the fans became very noticeable, not screaming banshees admittedly, but still pretty loud while the temperature was kept at a toasty 76°C.
But it’s this overclocked performance which has us leaning more towards the new Corsair cooler. When you’re thrashing your silicon with high frequencies, you want it to get back down to its idle temp as quickly as possible and the S24 takes far longer than the H110i GT and its similarly fat fans. Overall then, the S24 is a neat, simple, expandable AIO cooler, but the slow peak-to-idle performance and loud fans makes it a tough choice for the serial overclocker. – Simon Crisp
SPECIFICATIONS
Socket compatibility - Intel and AMD
Water block - Pure copper
Fan(s) - 2 x 120mm
Radiator dimensions (L x W x H) - 275 x 124 x 30mm
Warranty - Two years