Thermal PerformanceFor CPU water block thermal performance, I usually test on both my Intel Core i7-5960X and Core i7-4770K test setups, but the latter finally gave up midway after years of testing. As such, I used 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 it 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 completed the loop. The GPU used was not placed in the loop so that the only source of heat was the CPU and, thus, the CPU block itself. Average flow rate was set to 1 GPM and calibrated in-line temperature sensors were used to measure the coolant's temperature.
Everything required was placed inside a hotbox, and the ambient temperature was set to 25 °C. Gelid GC-Extreme was used as the thermal paste of choice and cure time was taken into consideration. Three separate mounts/runs were done for statistical accuracy and to remove the chance of any mounting-related anomalies. For each run, a 90 minute Intel XTU stability test was performed. XTU is a stability test from HWBot that uses a custom preset of Prime 95 (no AVR), which ensured the load is uniform on each run. CPU core temperatures were measured using Aida64, and the average core temperature was recorded at the end of each run. A delta T of CPU core and loop temperature was thus calculated for each run, with an average delta T that was then obtained across all three runs. This way, the cooling solution is taken out of the picture. The effect of block orientation was also tested, and the best orientation was used for these runs, with the result shown below.
The more standard cuplex kryos NEXT was already a fantastic block and outperformed everything else here, and the VARIO feature in this new review sample version took it further ahead. In fact, despite the entire field being so closely packed together, the VARIO technology alone resulted in a larger decrease in the delta T numbers than the block designs from various manufacturers. Of course, this is a result of my particular CPU IHS being somewhat different from what Aqua Computer scanned and averaged for, and your results may vary. They say they have observed as much as 2 °C less due to VARIO optimization on some CPUs as well, so this is definitely working well and not just marketing fluff.