Performance
Coolers as high-end as these have absolutely no trouble in cooling an overclocked and over-volted Intel Core i7-4770K processor. The Hydro Series H110i GT holds a slight performance advantage over the Noctua NH-D15 when both coolers are in an out-of-the-box state, but what's interesting is what happens when fan speed is reduced.
Using our system BIOS and the Corsair Link software, we were able to minimise noise by reducing the speed of both the Noctua and Corsair fans to around 500RPM. In this quiet state, the NH-D15 is able to continue delivering excellent temps aided by a giant heatsink, but the performance of the Hydro Series H110i GT drops off dramatically.
Both coolers can deliver excellent temps, but only one can keep noise levels down to a minimum. The CPU cooler is the most prominent source of noise in our test platform, and with the Noctua NH-D15 installed, you can barely hear it. Indeed, dial the fan speed down to quiet and it's hard to tell the PC is turned on.
Corsair's Hydro Series H110i GT isn't quite as elegant, as the pump, which operates at over 2,000RPM, can always be heard. The noise output is best described as a constant hum when the system idles, and though we wouldn't go as far as to call it obtrusive, it's definitely a long way from silent. The noise readings also highlight a good reason to use the Link software: by default, the fans get very noisy under load, and you will want to modify the speed curve in order to keep noise levels in check.
The gap in noise between the air- and liquid-cooled solutions probably wouldn't be as pronounced on older systems with other loud-running components. On a modern-day build with silent SSDs and high-end graphics cards that are passive when idle, the CPU cooler becomes the primary contributor to noise. In this scenario, the difference between the air and liquid coolers can be quite dramatic.
