Cooler Comparison Testing
Cooler Testing Methods
To best gage the quality of the system coolers under review, system CPU temperature and cooling system audio measurements were taken with the CPU idle and under load. To replicate CPU idle conditions, the system was rebooted and allowed to sit idle for 10 minutes. To replicate a stress system load on the Z77-based system, a combination of LinX and FurMark were run over a 30 minute period with LinX running for 500 loops with Memory set to All and FurMark running at 1280×1024 resolution and 2x MSAA in stress test mode. For the Z87-based system testing, Aida64 System Stability Test was used in conjunction with FurMark for 30 minutes per run. After each run, the system was shut down and allowed to rest for 10 minutes to cool down. Then the CPU cooler was removed, cleaned, and remounted to the CPU with fresh thermal paste applied. This procedure was repeated a total of 12 times for each cooler – three times each for the stock speed and overclocking runs on the Z77 and Z87-based systems.
Temperature measurements were taken directly from the CPU thermistors using RealTemp (the newer Tech|Inferno edition). For the Z77-based systems, the highest recorded value for idle and load temperature were used for the run. Because of the volatile nature of the Haswell thermistor readings, the Z87-based system temperatures were measured in a different manner. For idle temperatures, the highest recorded value was used for the run. For load temperatures, a series of three values were notated: the average (high and low) across all cores, the average (high and low) across the single highest core, and the high temperature.
To adequately measure the Antec Kuhler H2O 1250 liquid cooler performance, performance testing was done for all scenarios under three operational conditions – dual fan with system speed regulation, quad fan with system speed regulation, and dual fan at full speed. In system speed regulation modes, the fans are connected to the unit's fan connectors for speed regulation via the unit's control PCB. In full speed mode, the unit's stock fans were directly connected to the PSU and run at full speed. For quad fan operating mode, Antec fans rated for 2500RPM fan speed were used for testing.
Note that the temperature values are reported as deltas rather than absolute temperatures with the delta value reported calculated as CPU temperature – ambient temperature. For all tests, room ambient temperature was maintained between 23-27C. Sound measurements of the system cooler where taken with the sound meter placed 3 feet away from the system with all other devices in the room silenced. The Sound Meter Pro applet on a Samsung Galaxy S3 mobile phone was used to measure decibel level.
Intel Z77-based Ivy Bridge System Testing
CPU Stock Speed Testing
The CPU stock speed testing was conducted with the BIOS defaults set (including enabling of the CPU-integrated graphics processor) with Turbo Mode disabled, equating to a 3.4GHz CPU speed, 1600MHz memory speed, and 100MHz base clock. The Intel Speedstep functionality remained enabled for the duration of the testing to get realistic CPU idle performance conditions.
When tested with a stock speed Ivy Bridge CPU, the Kuhler H2O 1250 came in at the bottom end of the performance curve, surprisingly enough. There was negligible difference between the three operating modes of the cooler, indicating that the unit was not stressed by the CPU heat load.
CPU Overclocked Speed Testing
The CPU overclocked speed testing was conducted with known stable settings from a previous board review with Turbo Mode disabled, equating to a 4.4GHz CPU speed, 1960MHz memory speed, and 105MHz base clock. Also, the CPU-integrated graphics processor was disabled to reduce the processor heat generation. The Intel Speedstep functionality remained enabled for the duration of the testing to get realistic CPU idle performance conditions.
Board voltage settings were configured as follows:
- CPU Core Voltage – 1.2750
- CPU I/O Voltage – 1.150
- DRAM Voltage – 1.6255
- System Agent Voltage(SA) – 1.0850
- CPU PLL Voltage – 1.7500
- PCH 1.05 – 1.0995
The Kuhler H2O 1250 cooler performs well using the overclocked Ivy Bridge CPU with performance coming close to the top performers when fans are set to run at full speed. Cooler performance scales as expected with measured temps reduced in quad fan mode as well as in two fan full speed mode, in comparison to the cooler operating at stock two fan mode.
Intel Z87-based Haswell System Testing
CPU Stock Speed Testing
The CPU stock speed testing was conducted with the BIOS defaults set for the CPU (including enabling of the CPU-integrated graphics processor) and Turbo Mode disabled, equating to a 3.4GHz CPU speed, 1600MHz memory speed, and 100MHz base clock. The Intel Speedstep functionality remained enabled for the duration of the testing to get realistic CPU idle performance conditions.
Similar to the cooler's performance with the Ivy Bridge CPU, the Kuhler H2O 1250 cooler performs on par with the other tested coolers. There is minimal difference between the three operating modes of the cooler, again indicating the lack of heat stress on the cooler.
CPU Overclocked Speed Testing
The CPU overclocked speed testing was conducted with known stable settings from a previous board review with Turbo Mode disabled, equating to a 4.68GHz CPU speed, 1780MHz memory speed, 4.0GHZ ring bus speed, and 167MHz base clock. Also, the CPU-integrated graphics processor was disabled to reduce the processor heat generation. The Intel Speedstep functionality remained enabled for the duration of the testing to get realistic CPU idle performance conditions.
Board voltage settings were configured as follows:
- CPU Core Voltage – 1.25 + 0.005
- VCCIN Voltage – 1.90
- DRAM Voltage – 1.55
- CPU Ring Voltage – 1.125 + 0.005
- CPU SA Voltage Offset – +0.100
- CPU IO Analogue Voltage Offset – +0.100
- CPU IO Digital Voltage Offset – +0.100
- PCH 1.05 Voltage – 1.120
With an overclocked Hawell-based processor, the Kuhler H2O 1250 performs at bottom of the pack. However, the cooler's performance remains within 5 Celsius of the top performing cooler. Here, we do not see the performance scaling between modes as expected with the auto regulated dual and quad fan modes performing equally. Only running the fans at full speed decreases the load temperatures of the unit. This type of performance indicates that we are approaching the performance thresholds of the Antec cooler.
Sound Testing
The Antec Kuhler H2O 1250 cooler was whisper quiet in stock operating mode, almost inaudible over the case or graphics card fans. At full speed, the unit's fan noise drowns out all other system fans by a significant margin, making this operational mode highly undesirable for the minimal performance gains.
Nice review. Thanks for not
Nice review. Thanks for not caving and giving it an unwarranted award. Now I know I can trust when you, Morry, give an award, it is warranted. Unfortunately, I cannot say that about many reviews on the site, though I generally think the reviews are excellent, nonetheless.
a small mistake on final page
a small mistake on final page of the review. under pricing you guys talk about pricing of silverstone tundra aio rather than the antec unit reviewed here. please correct that. a good thorough review as usual.
Thanks for the feedback, this
Thanks for the feedback, this has been corrected…
When I first saw this design,
When I first saw this design, I thought it was pretty clever. Then later, I’ve been thinking about it and now I’m not so sure. Having the fans locked to the pumps isn’t really an advantage, you can’t regulate the fans alone, you can’t switch fans, really bulky etc. Not having the pump in the CPU block, you actually loose head pressure at the critical part of the system, the CPU block. I think this is the biggest part of it having worse performance compared to the Corsair unit. I haven’t seen the pumps taken apart (hint hint) but I suspect that they have had to take some short-cuts in the design there. For example, are they using a common axle for the pump and fan? Or are they compartmentalized (using permanent magnets) to prevent leaking seals? Pretty big in considering the longevity of the unit.
And the mounting thing is just poorly done on such an expensive unit. Inexcusable.
Have one of these coming in
Have one of these coming in the mail now. Going to replace my push/pull FX cooling. Hoping I get some improvement on my 8120 Black Edition.