NZXT’s Kraken X72 closed-loop liquid cooler is another in the XX2 series, following the 280mm X62 that we previously reviewed. The X72 is a 360mm cooler, putting it in more direct competition with the Corsair H150i Pro (the first to feature a 6th-gen pump) and Fractal S36, and indirect competition – in performance only – with the EVGA CLC 280.
NZXT’s X72 costs $200, making it one of the most expensive CLCs on the market. The Floe 360 lands at around $184, the EK Phoenix 360 – a semi-open solution – is the only one that lands significantly higher. The X72 still uses the same pump design as when we tore-down the X42, running Asetek’s 5th Gen pump and a custom, NZXT-designed PCB for RGB lighting effects. Functionally, 5th Gen has proven to be marginally superior – technically – to its 6th Gen for outright cooling performance. We’re talking nearly margins of error. The newest generation is presently only used on Corsair’s H150i and H115i Pro products, as Corsair largely dictated what went into the 6th generation. Major differences are made-up by the metal impeller, similar to the one used by Dynatron in old Antec Kuhler products, rather than a 3-prong plastic impeller. These don’t perform differently in terms of thermals, but there should be reduced susceptibility to heated liquid, and theoretically reduced hotspots as a result of the new 6th Generation design. That doesn’t manifest in outright performance, but might manifest in endurance. We won’t know for a few years, realistically.
Our primary tests for the NZXT Kraken X72 review and benchmark include the following:
- 100% fan / 100% pump
- 100% fan / silent pump
- 63% fan (40dBA)
Before Vega buried Threadripper, we noted interest in conducting a simple A/B comparison between Noctua’s new TR4-sized coldplate (the full-coverage plate) and their older LGA115X-sized coldplate. Clearly, the LGA115X cooler isn’t meant to be used with Threadripper – but it offered a unique opportunity, as the two units are largely the same aside from coldplate coverage. This grants an easy means to run an A/B comparison; although we can’t draw conclusions to all coldplates and coolers, we can at least see what Noctua’s efforts did for them on the Threadripper front.
Noctua’s NH-U14S cooler possesses the same heatpipe count and arrangement, the same (or remarkably similar) fin stack, and the same fan – though we controlled for that by using the same fan for each unit. The only difference is the coldplate, as far as we can tell, and so we’re able to more easily measure performance deltas resultant primarily from the coldplate coverage change. Noctua’s LGA115X version, clearly not for TR4, wouldn’t cover the entire die area of even one module under the HIS. The smaller plate maximally covers about 30% of the die area, just eyeballing it, and doesn’t make direct contact to the rest. This is less coverage than the Asetek CLCs, which at least make contact with the entire TR4 die area, if not the entire IHS. Noctua modified their unit to equip a full-coverage plate as a response, including the unique mounting hardware that TR4 needs.
The LGA115X NH-U14S doesn’t natively mount to Threadripper motherboards. We modded the NH-U14S TR4 cooler’s mounting hardware with a couple of holes, aligning those with the LGA115X holes, then routed screws and nuts through those. A rubber bumper was placed between the mounting hardware and the base of the cooler, used to help ensure even and adequate mounting pressure. We show a short clip of the modding process in our above video.
Following an initial look at thermal compound spread on AMD’s Threadripper 1950X, we immediately revisited an old, retired discussion: Thermal paste application methods and which one is “best” for a larger IHS. With most of the relatively small CPUs, like the desktop-grade Intel and AMD CPUs, it’s more or less been determined that there’s no real, appreciable difference in application methods. Sure – you might get one degree Centigrade here or there, but the vast majority of users will be just fine with the “blob” method. As long as there’s enough compound, it’ll spread fairly evenly across Intel i3/i5/i7 non-HEDT CPUs and across Ryzen or FX CPUs.
Threadripper feels different: It’s huge, with the top of the IHS measuring at 68x51mm, and significantly wider on one axis. Threadripper also has a unique arrangement of silicon, with four “dies” spread across the substrate. AMD has told us that only two of the dies are active and that it should be the same two on every Threadripper CPU, with the other two being branded “silicon substrate interposers.” Speaking with Der8auer, we believe there may be more to this story than what we’re told. Der8auer is investigating further and will be posting coverage on his own channel as he learns more.
Anyway, we’re interested in how different thermal compound spreading methods may benefit Threadripper specifically. Testing will focus on the “blob” method, X-pattern, parallel lines pattern, Asetek’s stock pattern, and AMD’s recommended five-point pattern. Threadripper’s die layout looks like this, for a visual aid:
Because of the spacing centrally, we are most concerned about covering the two clusters of dies, not the center of the IHS; that said, it’s still a good idea to cover the center as that is where the cooler’s copper density is located and most efficient.
Our video version of this content uses a sheet of Plexiglass to illustrate how compound spreads as it is applied. As we state later in the video, this is a nice, easy mode of visualization, but not really an accurate way to show how the compound spreads when under the real mounting force of a socketed cooler. For that, we later applied the same NZXT Kraken X62 cooler with each method, then took photos to show before/after cooler installation. Thermal testing was also performed. Seeing as AMD has permitted several other outlets to post their thermal results already, we figured we'd add ours to the growing pool of testing.
Under guidelines by AMD that we could show Threadripper CPU installation and cooler installation, we figured it’d also be pertinent to show cooler coverage on TR and RAM clearance. These all fall under the “installation” bucket and normally wouldn’t get attention from us, but Threadripper’s uniquely sized socket with uniquely positioned dies demands more instruction.
Threadripper thermal compound & coldplate coverage has been a primary topic of discussion since we first showed motherboards at Computex. We’ve generally offered that, theoretically, coldplate coverage should be “fine” as long as the two Threadripper CPU dies are adequately covered by the coldplate. In order to determine once and for all whether Asetek coolers will cover the IHS appropriately, seeing as that’s what TR ships with, we mapped out the dies on one of our samples, then compared that to CLC thermal paste silk screens, coldplates, and applied thermal compound.
Deepcool was at Computex this year with what seemed like an emphasis on cases and RGB lighting, although they did have a new CPU cooler to show off. Many of these cases seem to be updated models of previously announced cases at CES 2017, which are still pending release in the North America market.
Fractal’s Celsius S36 debuts alongside the company’s S24, coolers sized at 360mm and 240mm, respectively. The Celsius series uses an Asetek Gen5 pump, identical to the pump found on the EVGA CLC, NZXT X42/52/62, and Corsair H115i/H100iV2 coolers. This is a semi-custom Asetek solution that’s been loosely customized by Fractal Design, primarily focusing on the addition of G1/4” fittings (rad-side only), on-pump speed tuning, and an on-rad fan hub. It’s not as customized as, say, the NZXT Kraken series, but NZXT’s products also run more expensive. Fractal is looking at a launch price of $120 for the S36 that we’re reviewing today, and $110 for the S24.
Our focuses are on thermals and noise – not that you can focus on much else when talking coolers – with some new testing that looks at normalized noise output. We debuted this testing in our ASUS ROG Strix review and have carried it over to coolers.
Fractal’s coolers use 120mm fans that run a maximum RPM nearing 2000, with variable pump RPM from ~2000~3000. In our testing, though, it seemed a little simpler than that – pump RPM is based on liquid temp, and as we found in our 7700K review (the hottest CPU we've tested), liquid temp never really exceeds 30C. Given Fractal's curve, that means the pump stays at 2000RPM almost all the time. Rather than use software or suggest straight BIOS control – which we prefer – Fractal’s gone with a toggleable pump plate that switches into auto or PWM options. We’ve tested variable pump speeds in the past and haven’t found major differences in cooling efficacy, which is more heavily relegated to the fan spec and radiator size than anything else. This is more of a noise impact. We tested using the default, out-of-box “auto” setting, which kept our pump RPM fixed nearly perfectly at ~1960 throughout the tests (liquid temperature doesn't ramp up enough to push higher).
Fan speeds were manually controlled for the tests, though users could connect the fans to the on-rad hub. More on this in the conclusion.
Let’s get on with the testing, then run through the accessories and conclusion.
At the tail-end of our CES 2017 coverage, our visit to the Thermaltake showroom provided a look at upcoming cooling products – as the name might suggest – alongside some spin-offs of existing product lines. The more playful side of the room was outfitted with an original Donkey Kong arcade cabinet look-alike, a case mod by “Thermal Mike” for which we’ll post a separate video, while the rest of the room featured liquid and air cooling products.
Today's focus is on the Thermaltake P1 TG mini-ITX wall-mount enclosure, the Rainbow AIO CLC, and the Engine 27 Sandia-style ($50) cooler.
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