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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

CPU Cooler Final Thoughts

Although all-in-one water cooling kits existed years before Corsair introduced the H50 in June, 2009, the result of this Asetek/Corsair collaboration provided much better performance than previous efforts. While the H50 didn't compete with high-end air coolers, it provided a quiet alternative to mid-range coolers for mild overclocking, and you could enhance its performance significantly by adding a second fan.

Two of the best ways to increase a heat sink's performance are to increase the surface area of the "heat exchanger" (where heat is transferred to the air), and to move more air over the heat exchanger. Corsair adopted both tactics with the Hydro Series H70, doubling the thickness of the radiator and adding another fan. Doubling the radiator thickness gives the same surface area as would increasing the radiator size to 120x240mm, but the latter solution would severely restrict the number of cases the cooler could be used in.

The thicker radiator and dual fans increase the performance of the H70 tremendously, giving it a solid 7.8 degree lead over the H50 when compared with the stock fans, and a 3.4 degree lead when both are configured with the high-speed Delta fan. Since the pump assembly is obviously different, it's possible that the internal heat plate design has changed or that the pump has a higher flow rate, but if so, neither Asetek nor Corsair are saying.

In previous reviews I've noted how rapidly the CPU cooler market was advancing, with new designs and new performance benchmarks appearing so frequently that it was hard to keep up. We seem to be approaching an asymptote, though: the size of air coolers is reaching the constraints imposed by standard computer cases, and performance is leveling off. Since any retail CPU is shipped with a perfectly good CPU cooler in the box, you might think that the only reason to purchase an aftermarket cooler is performance. While this is certainly the primary consideration, there are others, such as acoustics (how loud the cooler is) and aesthetics (for windowed cases). Also, bear in mind that not every cooler works in every situation: top-performing air coolers tend to be both large and expensive, and are overkill for all but the hottest, most overclocked systems. There's room in the market for many different types of coolers, and the best solution for you is probably not the best solution for me.


While water coolers have improved since 2009, so have air coolers. For $109.99 at Newegg, the Corsair H70 is significantly more expensive than a Prolimatech Super Mega or Thermalright Venomous X, although equipping the latter two coolers with two high-performance fans would narrow the price gap.

Normally, our high-speed fan tests provide a good indication of relative cooler performance, but I think in this case the H70's thick radiator threw the results off a bit, since it probably requires a higher static pressure for good performance than do the air coolers. If you do replace the fans on this cooler, you should stick with the dual-fan configuration...but the stock fans on "low" provide an excellent balance of performance and noise in most cases.

Corsair Hydro Series H70 Conclusion

Please remember that these test results reflect our experience with each cooler on a specific motherboard, with a specific processor, BIOS revision, BCLK and voltage settings, and test programs. The results of this test cannot be directly compared to other tests since many factors will have changed.

Installing the Corsair H70 is relatively easy if you read the directions first and take your time. The "universal" Intel backplate (on AMD systems, the stock motherboard backplate is used) keeps the parts count (and price) down, but I prefer the more robust mounting system design of Asetek's original systems.

The performance of the Corsair H70 was very good, easily beating all the other water coolers in this test, although it was still outperformed by less expensive air coolers. Doubling the radiator thickness enables the H70 to double the surface area of its heat exchanger, which when aided by its dual fans provided a real increase in performance. I'd prefer to see PWM fans like the Cooler Master V6 GT uses, so the computer could control the fan speed. Having to plug in resistor cables to control fan speed seems a crude solution, especially at this price level.

The construction quality of the H70 was also very good: everything fit and worked correctly and the swivel mountings for the hoses pivoted freely. I have seen some water coolers arrive new in the box with bent or damaged fins, but the H70's radiator was pristine. I would prefer to see a more robust mounting system, though, since I think the clamping pressure might be a bit low with the current system.

The main reason to go with the H70 over a top-end air cooler is noise: while the V6 GT kept the processor 6.5 degrees cooler than did the H70 (with its fans on low), it did so at a substantial cost in noise. Also, if you transport your computer, the weight of a high end air cooler (all of which are two or more times heavier than Intel's recommended weight limit) can actually damage the motherboard if the computer is subjected to shocks; the tiny pump of the H70 is a featherweight in comparison to the kilogram or heavier weights of a dual-fan equipped Megahalems.

Cosmetically, the H70's rather dull, with all-black components and the Corsair label on the pump being the only adornment of any kind. While not everyone uses a windowed case, a little extra bling wouldn't hurt, especially in an era where even Intel puts LED lighting on their retail CPU coolers.

If you're interested in exploring water cooling, the Corsair Hydro Series H70 is a good introduction.


+ Good performance/noise balance with fans on low speed
+ Included "Y" and resistor cables for fans
+ Easy entry into water cooling
+ No maintenance required

Cons: Benchmark Reviews Seal of Approval

- Outperformed by less expensive air coolers
- Installation can be a bit tricky, pump mounting brackets seem flimsy
- Standard installation dumps hot hair back inside your case
- Cannot expand the system with chipset or GPU coolers
- Specifications for pump, fans seem to be secrets


  • Performance: 8.50
  • Appearance: 8.25
  • Construction: 9.25
  • Functionality: 8.75
  • Value: 7.75

Final Score: 8.5 out of 10.

Recommended: Benchmark Reviews Seal of Approval.

Is the Corsair Hydro H70 on your shopping list? We invite you to comment below or start a discussion in our Forum.

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# 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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