Cooling Efficiency

Intel Core i7 Platform

During this test session we managed to overclock our 45nm quad-core processor with the multiplier set at 21x and “Load-Line Calibration” enabled to 3.97 GHz (+48.9%). The nominal processor Vcore was increased to 1.3625 V (+13.5%) in the mainboard BIOS:

The memory voltage was at 1.62 V and its frequency was 1500 MHz (7-7-7-14_1T timings). All other parameters available in the mainboard BIOS and connected with CPU or memory overclocking remained unchanged (set to Auto).

The results of our tests on Intel Core i7 are given on the diagram below:

The thing we replaced in Thermaltake PW880i was the radiator with the fans and this resulted in a 1°C improvement with all three fans in quiet mode compared with the same operational mode of the Thermaltake radiator (two fans at 1020 RPM). When we increased the fan rotation speed to moderate 1170 RPM we gained another 3°C, then another 2°C when the ebm-pabst fans were working at their maximum speed, and another 2°C when we replaced the default fans with Noiseblocker ones at 1830 RPM. So, a higher-performance radiator and fans lowered the peak CPU temperature by 4°C in quiet mode and 3°C at maximum fan rotation speed of Alphacool and Thermaltake PW880i systems. Frankly speaking, it is not too much, but let’s not stop here and move on to see what happens when we replace the pump and expansion tank unit.

I would like to remind you that the claimed performance of Thermaltake PW880i is 500 l/h with 1.8 m maximum head, while Laing DDC should pump 420 l/h at 3.7 m maximum head. The liquid volume in the tanks is about the same. So how did this modification affect the results? Well, actually it practically didn’t. 1°C that the system with an alternative pump and tank managed to win is a very doubtful justification for this modification that is why let’s move on to the next step: replacing the processor water block.

It turned out that by installing Alphacool NexXxoS XP water block instead of Thermaltake PWB100 was the most significant modification for cooling efficiency, as it lowered the peak CPU temperature by 7-9°C! This is an excellent result, and if we also recall that Thermaltake PWB100 is not the default water block that comes with Thermaltake PW880i liquid-cooling system and already is 3°C more efficient than the default one, then the importance of Alphacool NexXxoS XP in the system becomes even greater.

Summing up the results of our Alphacool system tests on an Intel Core i7 platform we have to add that at comparable noise level this liquid-cooling system outperforms the best air cooler by 7°C in quiet mode and 9°C at maximum fan rotation speed. In conclusion I would like to offer you a screenshot showing maximum CPU overclocking with this system:

This is an excellent result at +26°C room temperature and 1.375 V processor core voltage.