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H100i fluid temp higher than CPU (in mITX case)


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Hey all


Thank you for your help. I am struggling a bit with the h100i v2 cooling system.


mITX case: Fractal 500

CPU: i7 6700k

Mainboard: Asus z170i pro gaming

Cooling: Corsair H100i v2

GPU: Asus Strix 970 GTX


The room I am using the PC is rather hot in summer (around 28C).


IDLE: 30-32C CPU

While gaming stable at: 34-36C CPU


So far so good, but the H100i is showing me the following temperature (I guess for the fluid?):


IDLE: 30-32C

While gaming going up to 44-45C, but remain stable up there


First of all: Is this normal? Is it safe to use the fluid at 44C? Because if I use another mode than my own custom curve the fans start roaring like crazy - unbearable sound.


Pump is running at full speed, however I adjusted the fans with a custom curve, because at 40C they get really loud (in quiet mode).

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It could be a H100iV2 issue, but you really need to attach two of CL4 [Home] tab screen shots to your post for idle and gaming so we can see all the temperatures and fan speeds.


Rather than posting half your PC specs it would be easier to help you if you added them all to your profile, so do this.

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  • 6 months later...

I am sorry to bump this thread. I'd also want to understand the highest temp of the pump/liquid on an H100i (mine's a V2). I looked at all the default profiles on CL4 and all of them set the fans to the fastest RPM at pump temps of 40 degrees Celsius and up.


Can I assume 40 degrees C and up is the temp I should watch out for?


Thank you!

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Corsair does not publish a maximum safe coolant temperature. From a practical standpoint, your CPU will hit the throttle point before the liquid could reach a dangerous level and the rubber is rated far beyond what you could reach in any circumstances. In short, there is no danger but it does take some tinkering to make the system livable.


The issue with designing the preset fan curves is your minimum starting temperature is always going to be based initially on your room temperature and effectively your local case ambient temperature inside the case. That is a shifting variable and no two set-ups are likely exactly the same. So what do you pick as the starting point? Corsair made it simple and went with standard room temperature (20-23C). Rather than 40C coolant temperature representing a danger point from a hardware perspective, it represents a massive change in the amount of heat in the system. It takes a very specific amount of wattage to raise the temperature of the volume of fluid in the unit by 17C to the 40C max fan point (less the amount of heat the radiator/fans can dissipate). If you have raised your coolant temperature by 17C from CPU waste heat alone, that represents a very large amount of heat that needs to be removed and the fans run at maximum in accordance.


Things get tricky when their are other sources of heat, including the natural environment and other hardware, like your GPU. Someone in the Tropics who cold boots up in a 32C room, will have an initial coolant temp of 32C and likely a few degrees warmer at idle. This person can blast the fans all they want, but they will never be able to reduce the CPU temperature below the 32C room temp or more probably the 34-35C case temp. For people in this position or anyone in a Summer temperate climate, you might need to up-shift your curve by the difference between your room temp and standard. So, if your room is 28C in Summer, create a manual curve that pushes the maximum up by 5C.


The GPU waste element is a further complication, particularly in small cases. Your internal case temp will become quite warm and that becomes the effective minimum coolant temp. This does affect your CPU temp by pushing it up by the same increase over the starting temp, but again you will not be able to lower the coolant or CPU temp below the local case temperature. You can try and lower through more case exhaust, but that is not always possible or practical. You could continue with the sliding temp scale model, but a more practical approach to is limit the fan speed to a noise level you can tolerate, then leave a little room and create a slant to maximum several degrees beyond what you ever see gaming. This should create tolerable gaming conditions, while still proving an audible alarm if things go beyond normal. The amount of air you put through the radiator is not likely to be the strong determining factor in CPU/coolant temps. The local case temp will play a much larger role. You can keep lowering fan speed until your see a definite increase in your coolant temps. Try to use the coolant temp as the marker. It is steady and measurable, unlike the very dynamic and instance specific CPU temps.

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once again, thank you for your assistance....your response put the sense to me. I was going to ask next if I can rely on the coolant temp rather than the CPU and you answered my question. I am now positive that sticking with the corsair stock/pre-defined profiles will do for me. Usually set at Performance mode as I use lower RPM fans.


it's still winter here and the thermostat on the basement where my PC is at is set to 21 degrees C. However, because the heater is a "stove", the flames emit heat coming only from one direction (not vents) thus creating a higher temp when the thermostat calls for heat. This makes the coolant detect a base temp of 28-31 degrees C and goes lower as the stove stops blowing warm air.


my PC most of the time is folding and really brings the CPU to work. temps on pump goes to 40-41 degrees C but goes down to 36-38 deg C after 10 minutes or once the temps have stabilized. I am comfortable on these temps...as the CPU stays 65-70 degrees C on high loads @ 1.275-1.296 volts (adaptive voltage).


Quick response!

Thanks again! \Ü/

Happy Panda here

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