Case fan curve settings with H100i Platinum

I just recently installed the H100i Platinum AIO cooler and had a question on how to configure the fan curves for my remaining case fans in iCue.

 

My build has 6x LL120 fans on the Obsidian 500D RGB case (2 fans pushing air over radiator on the top, 3 fans as intake in the front, and 1 exhaust fan in the back).

 

When I was air-cooling my CPU, I set my fan RPMs based on the Intel Core Package temps in iCue. Since 2 of my fans are controlled via the H100i now, do I keep my other 4 fan curves based on Core Package, or do I change it to pump temperature?

 

This is my first time working with an AIO cooler so I'm a novice when it comes to figuring out the fan optimization.

Get off the CPU core/package temps. Your case fans will do nothing to keep the underside of your CPU cool or increase the thermal conductivity through the cold plate. Your case fans do regulate the in/out air exchange for the case and the radiator fans are part of that as well with case ambient temperature changes the end result. If you want to see what CPU temp regulation looks like, try the any of the three presets (Quiet/Balanced/Extreme) for the case fans. I can't stand it and it is essentially not viable for any CPU after Haswell.

 

There are two easy choices for most people:

 

1) Custom curve. Click the + in the performance tab. Use the coolant temp (H100i Platinum Temp) as the sensor control variable in the Commander Pro tab in iCUE. Your goal is here to create some sort of balance between the intake volume of the front 3 vs the exhaust capability of the top/rear 3. The radiator will cut your airflow potential in half, so think of that as "1 fan" in terms of balancing. No matter what, this does not need to be exact by any means, but if the coolant temp is climbing either you have CPU load or the case is getting warmer. This covers both. Makes sense for people with predominately CPU heavy loads or multi-radiator set-ups.

 

2) GPU temp - This is the clear and obvious choice for the rear fan, but the front 3 can be set for this as well. Depending on how much heat your GPU shoots around (or your usage) it may be preferable to try and push as much GPU heat toward the back of the case and minimize the amount sucked through the radiator out the top. This is my preferred one with open air GPUs and is probably essential for multi-GPU builds. The cooler does its thing. The front and back deal with the GPU, by far the biggest heat source in the case.

 

**Note the Commander Pro cannot access either of these data sets when the software is not running. If you spend a lot of time with it closed for other programs or just hate the fan blast on boot, there is another recommendation. The T-sensors that came with the Commander Pro (in the box hopefully) are native to the device and do not require the software to be active, thus they fans stay in control at boot as well. To mimic coolant temp on the CPU radiator, run a sensor to the exhaust side up above. Exhaust temp is usually within 1-2C of coolant temp and will stay at that fixed offset making it very reliable. For the GPU temp, you either stick it above the back of the GPU by the outputs in back OR tape it to the back of the rear fan to measure true rear exhaust temp. Obviously this will not be the exactly the same as GPU temp, but as long as you have a decent range of temperature change, it is an effective control variable. You will need to learn the range for each placement, but once you do it is effective and consistent.

2) GPU temp - This is the clear and obvious choice for the rear fan, but the front 3 can be set for this as well. Depending on how much heat your GPU shoots around (or your usage) it may be preferable to try and push as much GPU heat toward the back of the case and minimize the amount sucked through the radiator out the top. This is my preferred one with open air GPUs and is probably essential for multi-GPU builds. The cooler does its thing. The front and back deal with the GPU, by far the biggest heat source in the case.

 

Thanks for your response. I think I should probably go the GPU temp route as I have a 2080Ti and I think that's going to get way hotter than my i7-8700. Do you have any advice on what the best curves would be for the GPU temp? Should the 3 intake fans have the same curve as the exhaust fan?

 

I'd prefer a mix of performance/noise control but I don't really know how to build that as a well-rounded curve.

Should the 3 intake fans have the same curve as the exhaust fan?

 

Probably not. Generally speaking for a standard front (in), top/rear (out) airflow the rear fan is going to run the fastest trying to move the GPU heat out. Also, in terms of balance it is essentially 3 v 2 on intake/exhaust, so the front three (which will sound louder anyway) can go a bit slower. You can set infinite fan curves in iCUE, so there is no reason to make them run on the same one.

 

It would be nice if you could bump up your case fans by 200 rpm and the temp dropped 5C. Never going to happen. Changes are slow and you really can't eliminate heat. You can keep them too slow and then the heat starts to pile on. There is no specific rpm required for the job. Always go to your noise tolerance level or until you get into thermal issues. 120mm fans are very weak below 750 rpm. They start to become considerably more effective at 1000 rpm. Most people will find them loud at 1500 rpm. You can probably find some happy ground in between.

Thanks a ton for your help! One final question - I have a custom curve set up for my GPU fans, would it make sense for my case fans to have a similar curve to the GPU? I kind of want a baseline to go off of so I'm not totally in the dark.

 

I was thinking of having the front fans mirror the same temperature cutoffs but at lower RPMs and have the exhaust fan in the back do the same but with higher RPMs.

No, let your GPU fans do their own thing. They have a separate job and only they can cool your GPU components. If your GPU temp is climbing those fans must respond. The case fans can not reduce GPU temp, but do keep it from being worse by moving the radiated heat elsewhere. GPU fans also tend to be shrill, so they have their own noise vs performance analysis.

Hi,

I just accidentally run into this thread while asking the same question, I know it's an old discussion but I thought it is better to chime in instead of opening a new thread.

c-attack, your info is very helpful and I also have a super hot 2080TI in my system which is more bothering than my 9900k @5ghz which is currently under control.

I have similar "standard" setup H100i platinum radiator at the top, two 140mm QL fans at the front and one QL 120 at the back.

 

1.What is your opinion about fixed RMP for the case fans? Just set them to reasonable speed? Maybe 60% for the rear fan and 50% for the front two?

Edited January 31, 2020 by Patishi

Hi,

I just accidentally run into this thread while asking the same question, I know it's an old discussion but I thought it is better to chime in instead of opening a new thread.

c-attack, your info is very helpful and I also have a super hot 2080TI in my system which is more bothering than my 9900k @5ghz which is currently under control.

I have similar "standard" setup H100i platinum radiator at the top, two 140mm QL fans at the front and one QL 120 at the back.

 

1.What is your opinion about fixed RMP for the case fans? Just set them to reasonable speed? Maybe 60% for the rear fan and 50% for the front two?

 

 

That is another way to handle load. If your loads moment are predictable (like gaming or a renders), you can set all fans to the highest level you are willing to accept. No need for them to change. Moderate speed to get the most cooling possible, but still stay below your noise tolerance.

 

2080 Ti GPUs are hot, but presumably the problem is the GPU diode temp ("GPU temp") and not the case temp is hitting 50C. Those are two different issues. If your case temp was 27 and now its 32C when gaming, the most you can reduce GPU temp is 5C with case fans -- the amount of ambient local heat. However, if the GPU temp is 85C, that might not be enough and the issue has to addressed with the GPU's own fans. Only those will really cool the circuit board. If your case temp is 50C, then you do have some case heat management issues and need more fans or a different flow pattern.

In case of top exhaust radiator setup, the only case fan that can help with CPU cooling somehow is the upper-front intake (the one that's closest to the radiator)? by bringing cool air from the outside and than the radiator fans can suck that air to cool the radiator? Am I right?

It also means that in cases where only the CPU gets hot, it doesn't matter if the rear exhaust case fan spin faster or not..it simply won't do anything (unlike with air coolers)

So it makes sense to set the upper front intake fan to max (cpu,gpu)?

Any thoughts?

Edited February 1, 2020 by Patishi

Case ambient temp is always your baseline temperature for everything. PC powered off, internal air temp is 29C, everything in the box is ~29C. When you are using the machine, then things heat up from voltage, but the local air temp is the still the baseline. So yes, ambient temp matters. If your case ambient temp increase +5C, then all components increase +5C in their temps. So cooler is better, but typically you see single digit changes and that means that no matter how much airflow you have, you can only reduce hardware temps by single digits values at any speed, back to the starting temp.

 

So sure -5C is nice, but if you are looking at CPU/GPU temps, a huge portion of that is voltage based and unique to device. I am idling at 30C, I load up Prime95 and hit 85C instantly. That is 55C of voltage based temp change. Minus 5C would be nice but it's not the case temp that makes the CPU 85C. It's the voltage. Same thing on the GPU.

 

In terms of your top mounted radiator, there is a relationship between intake air in one one side and its ability to remove heat from the other. However, the real factor that you will see in your daily use is case ambient temp = minimum coolant temp. The top 3 inches of your case are naturally warmer than the front rail. Usually about 2-3 even at low idle. Thus radiator in the top usually means +2-3C warmer on the CPU then front mount.

 

It's pretty hard to "starve the radiator fans" for air, unless you smother them with an dust filter. Also remember the radiator itself is a massive restriction to airflow. A fan at maximum will move about half of its listed volume specification. So in very basic terms, the front fan only needs to be moving half as fast as the radiator fans to keep the air exchange even. That's not hard to achieve. Higher front fan speed likely has more value in cooling RAM, m.2 drives, or the motherboard in general. The rear fan is the one to manipulate vs GPU temp. You would prefer most of the GPU waste heat exit through there and not through the CPU radiator above. If you are playing a game and you get CPU coolant temps of +10C or more, it is likely you are heating the entire case or a fair amount of heat is being pushed through the radiator. If your radiator intake air temp is 37C, eventually the whole loop is going to be 37C before any CPU heat is added. This often becomes visible in console port games with very low CPU usage (25% or less) and strong GPU load. Somehow your CPU temps seem high. Likely case temp related.

 

I don't see any reason to run the front two fans at different speeds unless there is some physical obstacle or rationale. Let them act together. Front fans are often seems nosier because of location and front fascia design. If you don't need to blast them, don't.

Thank you very much for the detailed answer, very appreciated :)

The reason I decided to go for automatic fan curve is because I got tired of always switching around between fixed rpm modes when I'm gaming, I prefer the software to control that automatically for me.

So right now I set the rear exhaust fan to go by the GPU temp (it reaches 100% fan speed at 70c GPU temp..a little aggressive but like I said my GPU is getting super hot very fast) and the lower front intake fan set to obey the GPU sensor as well with a little bit less aggressive curve.

should I make the upper front intake to match the bottom one?

 

You said that there is no need for excessive air intake in order to balance the air pressure (because of the top radiator), but can it hurt in some way if the fans will spin at 100% (assuming I don't mind the noise)?

Edited February 1, 2020 by Patishi

Sure, it possible to shift the airflow balance in a way that produces less desirable results based on your set-up. However, that is going to be unique to hardware, case, fans, etc., so you have to play around and see.

 

Don't worry too much about the balance. It does not need to be an exact match and typically you only see negative consequences at the very extreme exaggerations of this -- back fan full speed, front fans off, top fans whatever.. and it draws air in through some vents on the bottom. Not necessarily a negative consequence anyway. Most of the talk about "pressure balance" centers around theories of dust build up with negative pressure. Frankly, it doesn't matter. If you have a dusty room, it will get inside, outside, and everywhere else. If you don't, dust does not magically appear. If a dust particle gets near an intake fan, it goes in. Does not matter what your other fans are doing. Either a dust filter catches it, or it doesn't. The only people that might worry about this stuff are those will glass panel cases that do not seal on the sides and are not filtered there either. That is the limited scenario where you might want a lot of intake pressure to push air out those gaps vs sucking air in. Then again, if it's a fairly clean room, it still won't matter.

Edited February 1, 2020 by c-attack

Thx. I'm overthinking it :)