Which sensor do you match your case fans to?

Relentless81

Relentless81

Relentless81

Soldato
Joined
18 May 2010
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12,832
Hi,

This is driving me nuts and I'm sure its simple and I'm over thinking it but was wondering what everyone else does?

On my previous system I matched all my case fans to CPU, CPU ramps up and so do case fans which was perfect.

On this system my CPU tends to spike the temp whilst doing basic tasks such as browsing the internet, this is driving me nuts because the case fans are ramping up and down all the time, not much I can do about the CPU as its a part of XFR so I tried to set a manual fan curve for the case fans but this has no effect what so ever, case fans just sit at minimum RPM and dont ramp up with the CPU temp, probably a BIOS issue that will be fixed eventually, switch it back to preset manual or silent and they match the CPU again

So I'm wondering, if I match the case fans to the System Temp (Motherboard temp sensor) the case fans dont ramp up under basic tasks which is great, but this sensor always seems to sit around 30C so how are the fans supposed to ramp up if the temp doesnt increase by much if at all?

And what is weird is the plot for all the sensors is the same, eg -

I set Case fan to CPU and the chart makes sense.

I set Case fan to System Temp and the chart remains the same as the CPU and makes no sense.

Its funny how something so simple is so time consuming and frustrating!

Cheers
 
Thanks for the detailed info, I get what you're saying but let me try and explain a little better -

All fan headers are PWM and tied to CPU temp, 2 x Noctua AF14 intakes and 1 x Noctua S12 exhaust

I've changed minimum air flow from 550rpm to 750rpm this has no effect on CPU temps, the CPU will hit temp spike or hit the same temp in stress testing regardless of the minimum. The spike is called by XFR on a Ryzen 1600X which boosts the CPU and Voltage causing all of the fans to ramp and instantly cool the CPU back down to idle until I click a web page or something and it boosts again, this is unavoidable unless I OC it which I dont want to do.

The motherboard does everything listed above as standard, you simply tell each fan to use the CPU temp and set either, Normal, Silent or Manual. On Normal or Silent default curves I get the annoying ramping up and down in turn with CPU boosting.

What I want to understand is with System Temp sensor, it never really gets hot enough to ramp up the fans when the system is under load so setting the fans to that is pointless. Setting them to CPU is annoying due to ramping. So I'm kind of at a loss in terms of what to do.
 
You're right in a way, there is plenty of air but the default curve allows for the fans to ramp up and down too much between idle and boost temp at idle so to get around it I set a manual curve where between 30C and 50C the case fans stay at 30% and would only start to ramp up from 50C and up which would solve it apart from the fact manual curves dont seem to work, the fans just stay at minimum RPM even when the CPU temp increases which means there must be a BIOS issue

Maybe I just need to wait for that to be fixed and try the manual fan curve again
 
No not this one, I thought the same but there is no option to test the fans before setting a manual curve.

I'm going to have another go tonight, queue 3 hours of messing about, I'm pretty sure as soon as I change it to manual the fans will just sit at minimum rpm and not ramp up due to a bios issue

only preset curves seem to work
 
doyll said:
I'm confused.
You can't set manual curves like you said above
"so to get around it I set a manual curve where between 30C and 50C the case fans stay at 30% and would only start to ramp up from 50C and up which would solve it ".​
That should solve your problems.

What motherboard do you have?
Click to expand...

Yeah that's my point, manual curves don't work, soon as you set a manual curve the fans just sit at min rpm for that curve. Will confirm later

Rroff said:
The only case fan I've setup to be controlled by temperatures (CPU) is the rear exhaust fan and even then I have it set so that if it ramps up at all its reactive and aggressively so it doesn't ramp to small spikes, etc.
Click to expand...

what about your intakes?
 
Rroff said:
All my intakes (3x 140mm) are connected to a frontpanel (5.25 bay) fan controller and usually run at 600rpm though I slightly bump it up in warmer weather. I do have the 540 Air case though it probably doesn't work as well with a different size/layout case.
Click to expand...

I see, used to have that case they are good. I couldn't do that though I like automation and utilising the fans full range

I know I'm weird
 
lude1962 said:
I think your over thinking this, so system temp stays constant, that says to me case fans are working ok, and enough air is flowing through the case (or wrong sensor reading).
Run some stress tests, see if you can get system temp to increase, if it rises a lot the this would indicate not enough airflow from the case fans.
Click to expand...

Probably, I do with most things! System Temp doesn't budge in Aida64 (No GPU heat) or even Heaven (GPU Heat) It just sits around 30C so the fans dont ramp up. Not tried it with gaming, maybe I should game for an hour with case fans set to System Temp and see if they ramp up but if they dont then my CPU might get toasty
 
Thanks, managed to sort it I think. Would be happier with a more aggressive curve but if I set the case fans to System Temp if I give the GPU chance to heat the case up IE about half hour of gaming then the fans sit at just under 1000RPM each and keep the temps in check so I'm going to leave it at that

No ramping up and down now either because I cant hear the CPU fan doing that

Cheers
 
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