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Corsair Hydro H70 Liquid CPU Cooler E-mail
Reviews - Featured Reviews: Cooling
Written by David Ramsey   
Monday, 07 February 2011
Table of Contents: Page Index
Corsair Hydro H70 Liquid CPU Cooler
Closer Look: Corsair CWCH70
Corsair CWCH70 Detailed Features
Heatsink Test Methodology
Testing and Results
Final Thoughts and Conclusion

Heatsink Test Methodology

Benchmark Reviews is obsessed with testing CPU coolers, as our Cooling Section has demonstrated over the past few years. We've solicited suggestions from the enthusiast community, and received guidance from some of the most technical overclockers on the planet. As a result, our testing methodology has changed with every new edition of our Best CPU Cooler Performance series. Because of this, each article is really its own stand-alone product, and cannot be fairly compared to the others. Benchmark Reviews continues to test CPU coolers using the stock included fan (whenever applicable), and then replace it with a high-output fan for re-testing.

Manufacturers are not expected to enjoy this sort of comparison, since we level the playing field for all heat sinks by replacing their included fan with a common unit which is then used for every CPU cooler tested. Many manufacturers include fans with their heat sink products, but many 'stock' fans are high-RPM units that offer great airflow at the expense of obnoxiously loud noise levels, or, conversely, quiet fans that sacrifice performance for low noise. By using the same model of cooling fan throughout our heat sink tests, we can assure our results are comparable across the board. This is one of the more significant changes we have made to our test methodology, since many of the benchmark tests we have conducted in the past have compared the total package. Ultimately we're more interested in the discovering the best possible heat sink, and we believe that you'll feel the same way.

For each test, ambient room temperature levels were maintained within one degree of fluctuation, and measured at static points beside the test equipment with a digital thermometer. The Corsair H70 and the comparison coolers used a common Thermal Interface Material of our choosing (listed in the support equipment section below) for consistency. The processor received the same amount of thermal paste in every test, which covered the heat spreader with a thin nearly-transparent layer. The heat sink being tested was then laid down flat onto the CPU, and compressed to the motherboard using the supplied retaining mechanism. If the mounting mechanism used only two points of force, they were tightened in alternation; standard clip-style mounting with four securing points were compressed using the cross-over method. Once installed, the system was tested for a baseline reading prior to testing.

At the start of each test, the ambient room temperature was measured to track any fluctuation throughout the testing period. AIDA64 Extreme Edition is utilized to create 100% CPU-core loads and measure each individual processor core temperature. It's important to note that software-based temperature reading reflects the thermal output as reported from the CPU to the BIOS. For this reason, it is critically important (for us) to use the exact same software and BIOS versions throughout the entire test cycle, or the results will be incomparable. All of the units compared in our results were tested on the same motherboard using the same BIOS and software, with only the CPU-cooler product changing in each test. These readings are neither absolute nor calibrated, since every BIOS is programmed differently. Nevertheless, all results are still comparable and relative to each products in our test bed (see The Accuracy Myth section below).

Since our test processor reports core temperatures as a whole number and not in fractions, all test results utilize ADIA64 to report averages (within the statistics panel), which gives us more precise readings. The ambient room temperature levels were all recorded and accurate to one-tenth of a degree Celsius at the time of data collection.

When each cooler is tested, Benchmark Reviews makes certain to keep the hardware settings identical across the test platform. This enables us to clearly compare the performance of each product under identical conditions. Benchmark Reviews reports the thermal difference; for the purposes of this article, thermal difference (not the same as thermal delta) is calculated by subtracting the ambient room temperature from the recorded CPU temperature.

Please keep in mind that that these test results are only valid within the context of this particular test: as the saying goes, your mileage may vary.

Intel Test System

  • Processor: Intel Core i7-950 Bloomfield 3.06GHz LGA1366 130W Quad-Core Processor Model BX80601950, core voltage set to 1.35V
  • Motherboard: ASUS Sabertooth X58 Intel X58-Express chipset) with BIOS 0603, BCLK set to 175MHz for a processor speed of 4025MHz

Support Equipment

  • AIDA64 Extreme Edition version 1.50.1200
  • MG Chemicals Heat Transfer Compound 8610-60G
  • Stock fan (for heat sinks without fans): Thermalright TR-FDB-12-1600 (63.7CFM advertised)
  • High-speed fan: Delta AFC1212D (113CFM advertised)

All of the tests in this article have been conducted using vertical motherboard orientation, positioned upright in a traditional tower computer case. Air-cooled heat sinks are positioned so that heatpipe rods span horizontally, with the fan blowing air out the top of the chassis. The radiators of water coolers are mounted as per manufacturer instructions. In both cases, fans are connected directly to the power supply (rather than motherboard headers) and run at full speed during the test. At the start of our test period, the test system is powered on and AIDA64 system stability tests are started with Stress CPU and Stress FPU options selected. AIDA64 loads each CPU core to 100% usage, which drives the temperature to its highest point. Finally, once temperatures have sustained a plateau (no observed change in average temperatures for 5 minutes), the ending ambient room temperature and individual CPU core levels are recorded thus completing the first benchmark segment. The time to reach stable temperatures varied between 10 and 20 minutes for the heat sinks in this test; larger heat sinks typically take longer to stabilize.

The second test segment involves removing the stock cooling fan and replacing it with a high-output 120 mm Delta AFC1212D cooling fan, then running the same tests again.

Note: The Coolit Vantage A.L.C. is designed to drive its own PWM-controlled fan directly, and an alarm will sound continuously if the fan is disconnected. Since I don't believe anyone would ever run the cooler this way, I left the fan connected to the cooler (with the cooler set to "Extreme" mode) for stock fan testing. For high speed fan testing, I connected the Delta fan directly to the power supply, and ignored the alarm.

The Accuracy Myth

All modern processors incorporate an internal thermal diode that can be read by the motherboards' BIOS. While this diode and the motherboard are not calibrated and therefore may not display the actual true temperature, the degree of accuracy is constant. This means that if the diode reports 40°C when it's actually 43°C, then it will also report 60°C when it's truly 63°C. Since the design goal of any thermal solution is to keep the CPU core within allowable temperatures, a processor's internal diode is the most valid means of comparison between different heat sinks, or thermal compounds. The diode and motherboard may be incorrect by a small margin in relation to an actual calibrated temperature sensor, but they will be consistent in their margin of error every time.



# Idea.Succellus 2011-02-08 02:08
You could put a symbology of all your awards so newcomers know how good the product is according to the award.
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# RE: Idea.Olin Coles 2011-02-08 08:26
The final score is a 10-point value, and should be an easy indicator for newcomers.
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# RE: Corsair Hydro H70 Liquid CPU CoolerRobert17 2011-02-08 05:14
I purchased an H50 last year and have it configured to exhaust outside the case and find it's performance acceptable on a day-to-day basis. It's certainly an improvement over the stock CPU coolers, and reasonably priced for that uptick.

I'll add to your note regarding the 'secret' pump performance. Besides the fluid flow, the fluid itself makes a difference and custom systems certainly have another advantage here. Different fluids and additives can increase heat transfer by decent margins. So if one is involved in serious overclocking, an open system has many advantages. But the simple and sealed packages such as the ALC and Corsair offerings are, as you said, a reliable, quiet, affordable, and easy way to increase heat displacement from the CPU.

Also note, the dual fan, push/pull configuration mounted to the radiator doesn't necessarily increase the CFM across the radiator by doubling the air flow (think of a fan as a pump for the fluid named 'air'). The same air moves through one fan, across the radiator, and then through the second radiator, fan speeds being equal. The air doesn't 'hover' around the radiator but is drawn more efficiently across the fins, and consistent pressure is maintained. To move more air, the fan speeds must be increased. Just as with any fluids, to increase flow, pumps must increase the fluid pressure. Adding more in-line pumps (fans) that all run at the same RPM doesn't increase flow, just maintains consistent pressure.
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# RE: RE: Corsair Hydro H70 Liquid CPU CoolerDavid Ramsey 2011-02-08 11:46
A push-pull configuration probably won't double airflow, but it will certainly help compared to a single fan. For "thin" radiators a single fan of "x" CFM will probably provide more airflow than a push-pull config where each fan is "x/2" CFM, but I think this would not be the case with the H70's double-thick radiator, which offers much more resistance to airflow.
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# h50 performs betterBunzing 2011-02-08 06:30
I switched motherboards a couple of weeks ago and wrecked the backplate of the h50 when I had to take it of. Corsair for some reason put superglue on it and it didn't come of without force. So I thought I'd buy an h70 and get corsair to send me a new backplate and sell the h50. Don't think I'll be getting the new backplate though since corsair won't respond to emails.

The h70 however has to be placed in the top of my cooler master cosmos s because otherwise it would interfere with the side intake fan. It runs on 1600 rpm and makes a lot more noise then my h50 (also had two fans) and runs 5C higher then the h50. Both are configured as exhausts btw.

I don't understand what causes this difference. Offcourse the sound is understandable since I had two of my own thermaltake iscg fans on it running at 1000 rpm! But still the h70 with 1600 and bigger radiator is 5C above the h50 with 38C in idle and around 42c when playing games.

If or when I get the backplate I'll do some testing wether or not there still is a big difference when I put it up in the same configuration and use the same fans as the H70.
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# RE: h50 performs betterDavid Ramsey 2011-02-08 11:47
I'm surprised the H70 is turned in higher processor temps than your H50. If you feel ambitious, it would be interesting to remove your Cosmos' side fan, put the H70 in the back, and see if that makes a difference.
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# RE: RE: h50 performs betterBunzing 2011-02-13 09:33
I'll try that when I have the time. I'm curious to see if that makes the difference.
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# RE: RE: RE: h50 performs betterBunzing 2011-03-01 03:22
Well, I placed the h70 in the back with the side off and it did shave the temps a little when it comes to case temperture but the cpu only dropped like 1c. Now i've got my h50 in the back with a thermaltake iscg fan as a second fan at 1000rpm and I have to come back on the temperture as it does run a around 4 to 5c of degrees higher than the h70 (nothing like the diference i've seen in most benchmarks where it's more like 10c). For me the amount of decibels the h50 runs lower on is the deciding factor. The temps never hit 45c, so i'm good.
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# Area mattersRealNeil 2011-02-08 06:57
For better heat dissipation they should have gone for more radiator surface area instead of a thicker radiator. A 120mmX240mm area would cool more efficiently. I realize that it would affect the fitment into a number of cases, but many cases have incorporated a spot for two 120mm fans on the topside already. Since heat normally rises, placement of such a radiator at the top of a case, exhausting the hot air through the top would just work better. I have an Asetek-LCLC (low cost liquid cooling)and a Corsair H50 here, (both are MADE by Asetek, and both are identical too) I have them in push/pull with high flow and quieter fans on each of them. They are excellent cooling solutions for my two i7-870's, both running @3.93GHz.
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# RE: Area mattersDavid Ramsey 2011-02-08 11:52
Heat-- well, heated fluids-- do indeed rise, but even the feeblest fan will provide an order of magnitude more air flow than the convection currents off a hot radiator, so I don't think radiator positioning will make a noticeable (or even measurable) difference in performance (although another commenter here who's mounted his H70 rad at the top of his case is getting worse performance than with his H50 mounted at the back, which is the opposite of what you'd expect).

A double-thick 120mm radiator offers the same surface area as a single-thickness 120x240mm radiator, although I think the latter would probably have a performance advantage due to better air flow.
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# Koolance erm-2k3u + cpu-350 + ocz freezeJuanPabloC 2011-02-08 13:01
my i7 920 @ 2.8ghz works at 21°c with 11 blocks, at "full" load (WinRar benchmark test)cpu never goes over 28°c. (43°c at the cores)... measured with HWMonitor from

60°C ? ... at the cores?
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# RE: Koolance erm-2k3u + cpu-350 + ocz freezeOlin Coles 2011-02-08 13:14
That's because you're using a very weak test, Juan. Plus you're comparing apples to oranges. Why not download the free AIDA64 trial and run the CPU System Stability Test tool?
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# not goodcactus 2011-02-08 23:00
It surprises me that this cooler gets a good wrap from reviewers. As the benchmark shows a highend air cooler performs better than a H70 even with its high speed/loud fans.

A highend aircooler will operate cooler even with a(good)silent 1200RPM fan like the Scythe S-Flex. I know this because i have one and its virtually silent on a Thermalright cooler. I have tested many, many fans and only the best 1200RPM fans are virtually silent, fans spinning at 1600/2000 RPM are just ridiculous.

Why would you put up with noise and pay a lot more for H70 when you can have a cheaper and virtually silent high end cooler. I can only assume some people have never experienced a silent system or know what is possible or have been sucked in by "water" cooling marketting.

And before anyone says "You can run the H70 with 1200RPM fans" the H70 suffers badly with fans at that speed and you can add 10 Degrees to temps.
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# Helpful All in one Liquid Cooler ReviewJohn Darcy 2011-02-11 03:48
Thanks for the tips and dremmel tips that are actually tried and tested. I am sometimes fearful of attempting too many cutting operations,or any at all for that matter lest I do irreparable damage to something. It isnt as if I still couldnt , however i enjoy the reviews which actually do make alterations out of the box to make something work better.
I have a gpu which seems to make in non silent even at its factory de tuned super low power usage rates. as soon as it gets beyond 32% it is audible to my old ears and after 34% it is noisy. I have a good aftermarket cooler on one 5870 and it is quieter but not silent. so the notion of a silent system as far as the cpu cooler goes is out. But, there are some good 'quiet' fans which push a fair amount of air enough dramatically reduce my Phenom II 965 in the hot summer. I do not think these liquid all in ones ready for me and my price point as yet. It is good to know how much progress is being made. I have used enough of the well reviewed air cooler/heat sink types and changed fan with good sale silent fans or 100+ cfm represented ones with 'some' noise.
i enjoy the input here on this side of the review as well for the reservoir of experience and info.
your efforts are greatly appreciated here.
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