Thermal Performance

For CPU water block thermal performance, I use my Core i7-5960X on the ASUS Rampage V Extreme motherboard with the CPU overclocked to 4.4 GHz at 1.3 Vcore and paired with 4x4 GB Corsair Dominator Platinum DDR4 RAM at 2666 MHz (CAS16-16-16-18). A Swiftech MCP35x2 pump, an Aquaero 6 XT controller, and a Black Ice Nemesis GTX 480 radiator with Noiseblocker NB-eLoop B12-3 fans complete the loop. The GPU is not placed in the loop to make the only source of heat the CPU and, thus, the CPU block itself. Average flow rate is set to 1 GPM and calibrated in-line temperature sensors are used to measure the coolant's temperature.

Everything required is placed inside a hotbox, and the ambient temperature is set to 25 °C. Gelid GC-Extreme is used as the thermal paste of choice and cure time is taken into consideration. Three separate mounts/runs are done for statistical accuracy and to remove chances of any mounting-related anomalies. For each run, a 90 minute Intel XTU stability test is performed. XTU is a stability test from HWBot that uses a custom preset of Prime 95 (no AVX), which ensures the load is uniform on each run. CPU core temperatures are measured using Aida64, and the average core temperature is recorded at the end of each run. A delta T of CPU core and loop temperature is thus calculated for each run, with an average delta T that is then obtained across all three runs. This way, the cooling solution is taken out of the picture. The effect of block orientation is also tested, and the best orientation is used for these runs, with the result shown below.


Note that newer blocks are not necessarily designed with the now older Intel X99 platform in mind, which has a more concave-to-flat IHS instead of the convex-to-flat IHS we see in more CPUs today. I am working on updating my test system, and this may well be the last CPU block reviews before I migrate over to an Intel Z390 platform, but the Eisblock XPX did impress when it comes to pure thermal performance. Indeed, noting that the cooling engine itself is unchanged from when the original versions came out nearly three years ago, this remains one of the best performers to date. I suppose this is more telling about the lack of innovation when it comes to performance upgrades in CPU watercooling these days, with physics and internal heat transfer bottlenecks simply being too much. We will see how everything comes together on the next page, including how much value for money is offered by the Alphacool Eisblock XPX.