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Choosing a Corsair 240mm AIO — 240mm vs 280mm, plus H100i variants questions


intelfx
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Greetings.

 

I'm choosing a Corsair AIO to replace an air cooling setup for my 5950X CPU. My case only supports 120mm-wide coolers and radiators without modifications, so I'm looking to install a 240mm AIO (that is, the H100 series). Consequently, I have two questions.

 

1. What is the difference between the H100i variants, other than RGB capability (which I'm not interested in)?

Notably, the H100i PRO ($140) more $20 less MSRP than the H100i PRO XT ($120) — which is "better" (for your definition of better)?

 

2. Looking at the H100 series compared to the H115 series, the former uses high-RPM fans, but not the latter:

 

- H115 uses 1200 rpm fans providing 55.4 CFM airflow and 1.27 mm-H₂O of static pressure at the expense of 20.4 dB(A) noise, whereas

- H100 uses 2400 rpm fans providing 75 CFM airflow and 4.2 mm-H₂O of static pressure at the expense of 37 dB(A) noise.

 

Both radiators appear to have the same thickness, so the extra static pressure provided by the 2400 rpm fans is apparently not needed.

What is the reason for using much more fast and loud fans in the H100 series?

What will happen if I replace the high-RPM fans with their low-RPM equivalents or limit them to <1500 RPM (that's about as much noise as I can accept with my current fans)?

And on that topic, should I look into replacing the fans in general or the stock ones are optimal already?

 

Thanks for your responses.

Edited by intelfx
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1) It's mostly RGB differences as well as usual changes over time with new models.

 

H100i Pro (Asetek partner) - 3 fixed pump speeds (1100, 2160, 2850 rpm). 2xML120 fans 2400 rpm max. Fans are not RGB. Pump ring is a simple RGB LED acting as 1 unit. This is the only Corsair model with that ultra low 1100 rpm pump speed. It's good for quiet desktop work, but comes with a substantial penalty for using it for extended load. This unit has a good track record with few complaints and was generally well received.

 

H100i XT - (CoolIT partner) I am dropping the "Pro" part of its name because it is too confusing and it was not a direct replacement for the H100i Pro. The two co-existed, even if the XT version came later. Different pump unit, denser cooling fins offer theoretically better CPU temperatures, but that necessitates higher pump speeds. (3 fixed, 2100-2700). Some complaints on pump tone and the CoolIT models usually have a higher pitch. 2xML120 Non-RGB and same as Pro. (2400 rpm max). Pump LED is individually addressable. Radiators same dimensions on both.

 

I suppose we can say both of these have now been replaced by the Elite line (CoolIT). However, this is a large step in a direction you may not want, with OLED pump display, an external fans and lighting controller, and included RGB fans. Global manufacturing and supply did some weird things this year. At one point the Elite models that were plentiful were selling for the same as XT coolers. You obviously get far more in this package and the Pro and XT variations should be less.

 

 

2) One of the side effects of the AIO competition from so many sources is people tend to google up a review and then pick the one that came out on top in the temp tests. The problem is many reviews do not standardize the testing conditions of the cooler's variables, like pump speed or fan speed and run them "at the default values". As a result, manufacturers started sending out AIOs with 2700 rpm fans. The radiators and flow rates are all fairly similar, so in order to beat Brand X by 0.9C, you need more fan speed. The problem is none of that means anything back down at the 1000-1300 rpm where most people would like to stop. Very rarely do you see reviews test all units with fans locked at 700 rpm, 1100 rpm, etc. working up through a range of fan speeds. Any fan from any brand is going to be near deafening at 2700 rpm. While it sounds simple enough (slow down your fans!), believe it or not there are a lot users who never take control over their cooler. Plug it in, default values, never touch it again.

 

The Pro series AIOs were a response to that. The H115i Pro (280mm 2x140) came with 1200 rpm max fans instead of 2000 rpm. The H150i Pro (360mm 3x120) with 1600 rpm instead of 2400 rpm. Those same 1600 rpm max fans should have been on the H100i Pro, but well... people haven't changed and on a 240mm radiator you can still pull back 1-2C by going into crazy fan speed territory. However, these are all the same fans with the same blade geometry. The 2400 rpm version from an XT will move the same amount of air as the 1600 rpm version from a H150i Pro when both fans are running 1000 rpm. You must run the indicated speed in order to realize the increases airflow or pressure. We can have a separate and very long discussion about static pressure, but it is the amount of negative pressure required to reduce a fan's speed to 0 rpm. Therefore RPM is the single largest factor in the value. A tiny 40x40 fan will have a very nice SP value -- at 4800 rpm. You can imagine what that would sound like and it would still only move 9 cfm of air. Physical airflow through the radiator is what matters. Static pressure is slightly more useful when comparing to different fan geometries at the same RPM. In this case, all of these fans are the same and the 2400 rpm ML has the same SP value as the 1600 rpm ML when both fans run the same speed.

 

The ML fans on all of these are good OEM radiator fans. This was a big step up from prior generations that had inexpensive, but high speed fans with predictable results. I would start with them. If they are not performance intensive enough (doubtful), there is a very small group of fans we can look at. If they are not quiet enough (they are pretty quiet for radiator fans), there also is a small group of specialty fans we can look at. Mostly that would be about changing tone. All fans will have a different sounds profile when against a radiator vs free air or case mounted.

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Thank you for the in-depth response.

 

1) It's mostly RGB differences as well as usual changes over time with new models.

 

H100i Pro (Asetek partner) - 3 fixed pump speeds (1100, 2160, 2850 rpm). 2xML120 fans 2400 rpm max. Fans are not RGB. Pump ring is a simple RGB LED acting as 1 unit. This is the only Corsair model with that ultra low 1100 rpm pump speed. It's good for quiet desktop work, but comes with a substantial penalty for using it for extended load. This unit has a good track record with few complaints and was generally well received.

 

H100i XT - (CoolIT partner) I am dropping the "Pro" part of its name because it is too confusing and it was not a direct replacement for the H100i Pro. The two co-existed, even if the XT version came later. Different pump unit, denser cooling fins offer theoretically better CPU temperatures, but that necessitates higher pump speeds. (3 fixed, 2100-2700). Some complaints on pump tone and the CoolIT models usually have a higher pitch. 2xML120 Non-RGB and same as Pro. (2400 rpm max). Pump LED is individually addressable. Radiators same dimensions on both.

 

I suppose we can say both of these have now been replaced by the Elite line (CoolIT). However, this is a large step in a direction you may not want, with OLED pump display, an external fans and lighting controller, and included RGB fans. Global manufacturing and supply did some weird things this year. At one point the Elite models that were plentiful were selling for the same as XT coolers. You obviously get far more in this package and the Pro and XT variations should be less.

 

I see. So what you're saying is the Pro line is better at low loads (by virtue of having a low-speed capable pump), but the XT line is better at high sustained loads (by virtue of having a better coldplate design but at the expense of a purely high-speed pump).

 

Do I understand correctly that the Elite line has an even better coldplate together with a low-speed capable pump unit, and thus is a better fit for "hybrid" workloads?

 

2) One of the side effects of the AIO competition from so many sources is people tend to google up a review and then pick the one that came out on top in the temp tests. The problem is many reviews do not standardize the testing conditions of the cooler's variables, like pump speed or fan speed and run them "at the default values". As a result, manufacturers started sending out AIOs with 2700 rpm fans. The radiators and flow rates are all fairly similar, so in order to beat Brand X by 0.9C, you need more fan speed. The problem is none of that means anything back down at the 1000-1300 rpm where most people would like to stop. Very rarely do you see reviews test all units with fans locked at 700 rpm, 1100 rpm, etc. working up through a range of fan speeds. Any fan from any brand is going to be near deafening at 2700 rpm. While it sounds simple enough (slow down your fans!), believe it or not there are a lot users who never take control over their cooler. Plug it in, default values, never touch it again.

 

The Pro series AIOs were a response to that. The H115i Pro (280mm 2x140) came with 1200 rpm max fans instead of 2000 rpm. The H150i Pro (360mm 3x120) with 1600 rpm instead of 2400 rpm. Those same 1600 rpm max fans should have been on the H100i Pro, but well... people haven't changed and on a 240mm radiator you can still pull back 1-2C by going into crazy fan speed territory. However, these are all the same fans with the same blade geometry. The 2400 rpm version from an XT will move the same amount of air as the 1600 rpm version from a H150i Pro when both fans are running 1000 rpm. You must run the indicated speed in order to realize the increases airflow or pressure. We can have a separate and very long discussion about static pressure, but it is the amount of negative pressure required to reduce a fan's speed to 0 rpm. Therefore RPM is the single largest factor in the value. A tiny 40x40 fan will have a very nice SP value -- at 4800 rpm. You can imagine what that would sound like and it would still only move 9 cfm of air. Physical airflow through the radiator is what matters. Static pressure is slightly more useful when comparing to different fan geometries at the same RPM. In this case, all of these fans are the same and the 2400 rpm ML has the same SP value as the 1600 rpm ML when both fans run the same speed.

 

The ML fans on all of these are good OEM radiator fans. This was a big step up from prior generations that had inexpensive, but high speed fans with predictable results. I would start with them. If they are not performance intensive enough (doubtful), there is a very small group of fans we can look at. If they are not quiet enough (they are pretty quiet for radiator fans), there also is a small group of specialty fans we can look at. Mostly that would be about changing tone. All fans will have a different sounds profile when against a radiator vs free air or case mounted.

 

Understood.

Edited by intelfx
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I see. So what you're saying is the Pro line is better at low loads (by virtue of having a low-speed capable pump), but the XT line is better at high sustained loads (by virtue of having a better coldplate design but at the expense of a purely high-speed pump).

 

Sort of. Better is a relative term. The Pro line is without a doubt the one for quiet freaks. I use that term affectionately. I am one. It is the only unit that can run the pump at that really low level. So if you are someone who like to work quietly at your desk and you hear every sound within a 3 block radius, this is the one you should get. People have a tendency to "make their PC quiet" by shutting down fans and lowering everything else to the minimum possible level. In that state, pumps and HDDs are always going to ring through. My general advice for minor pump noise irritation is to turn the case fans up slightly. Fans make a more comfortable, diffuse sound. Pumps do not. It's a small high speed motor.

 

 

 

 

Do I understand correctly that the Elite line has an even better coldplate together with a low-speed capable pump unit, and thus is a better fit for "hybrid" workloads?

 

 

Of course, there is no free lunch. In order to squeeze another 1-2C out of something, you need to tighten tolerances and increase baseline levels. So the Platinum/XT coolers had a slightly more restrictive cold plate, but you can't let the fluid stall out in the chamber. The interesting bit is several new Elite owners are reporting noticeable improvements when coming from the XT/Platinum line on higher TDP or die size CPUs like 10900Ks and other x_99 CPUs. Unfortunately, I do not have any confirmed AMD data for you, but theoretically a 5950x would benefit. However, you also may have noticed the rather long thread however around this one in the cooling section asking for a reduction in pump speed on the Elite coolers. This is because they find the tone less than pleasing. So we are back to which is the higher priority - a few extra degrees of the CPU? Or assured peace and quiet on the desktop?

Edited by c-attack
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