Question CPU fan speed constantly spikes on idle ?

[pinocammino]

Hello people, new user here.
I just upgraded some pc components (Full PC specs in the end) and, while running some tests with OCCT to be sure that everything was working correctly, i noticed that, while the pc is idling, the CPU fan rpm keeps spiking every 1-2 seconds from 0 to 1200-1400 and back (screenshot attached) while every other case fan value remains static (like 20 rpm variance) the whole time. The fans are physically spinning the whole time, no variations in speed noticeable but ofc being the spikes at 1 seconds interval, momentum is also a factor and i think there isn't enough time to actually slow down.
During loads or stress tests the CPU fan behaviour seems what's to be expected, going up, the higher the CPU temp is and never spiking (second attached screenshot. Test is only 1 minute long just for screenshot purpose but i've been running longer ones with different loads and in all of them the fan behaviour seemed coherent to what should be expected and the temperature too seemed to stay in expected parameters).
This leads to my question, is this a normal behaviour for the cpu fan that i somehow always ignored (or changed in the last 6 years since last time i changed pc) or there is something weird going on?

PC Specs
Motherboard: MSI Z790 Gaming Plus WiFi
CPU: intel i7 14700k
GPU: PNY 3070 8GB
RAM: Corsair Vengeance GDDR5 6000 [2 x 16GB]
AIO: MSI MAG coreliquid m240
SSD: Crucial P3 Plus
PSU: MSI 850w 80+

Case has 1 120mm rear fan and 3 120mm front fans

ATTACHMENTS

https://imgur.com/a/usC24N0

View: https://imgur.com/a/usC24N0
Idle monitoring

https://imgur.com/a/ARmVoKE

View: https://imgur.com/a/ARmVoKE
Stress test

 

[Lutfij]

Welcome to the forums, newcomer!

I just upgraded some pc components
What were you working with prior if the above listed specs are of your system post-upgrade?

Case has 1 120mm rear fan and 3 120mm front fans
You forgot to mention the make and model of your case. Fans came bundled with the case or did you go for aftermarket options?

 

[pinocammino]

Thank you.
Forgive me but i won't be able to be as exhaustive as for the new spec cause i don't remember all the old components by heart and don't have them with me atm to check.

What were you working with prior if the above listed specs are of your system post-upgrade?
CPU intel i7 8700
MOBO MSI gaming pro carbon B360
GPU 3070 (this has been changed midway so stayed the same in new configuration waiting for serie 50xx)
RAM 2x8 corsair vengeance ddr4
AIO arctic liquid freezer 240 (not 100% sure on this one sorry but reasonably so)
SSD can't remember sorry, just that it was 512 gb and not the nvme version
CORSAIR RM 750w 80+
1 rear fan included with case (can't remember model)
2 front fan added in front (can't remember anything about those)
CASE again can't remember

You forgot to mention the make and model of your case. Fans came bundled with the case or did you go for aftermarket options?
You're right sorry.
Case is a MSI vampiric 010x. The rear fan is the case specific one. The 3 front ones i ordered them separately but, maybe in a not that smart way, i didn't specify anything to my retailer other than them to be 120mm so that they could fit the case, and i didn't really bother to check for model later. If it's really that important to know them (considering the cpu fan readings showing that behaviour belongs to the AIO) i guess i could check in the case if i can find the model without having to dismantle too much, otherwise i can phone my retailer and ask but that has to wait till monday.

Oh i forgot to mention that BIOS and motherboard firmware are both updated to the latest version (oct 9th 2024) same goes for driver and even Windows

 

[CountMike]

Thank you.
Forgive me but i won't be able to be as exhaustive as for the new spec cause i don't remember all the old components by heart and don't have them with me atm to check.

What were you working with prior if the above listed specs are of your system post-upgrade?
CPU intel i7 8700
MOBO MSI gaming pro carbon B360
GPU 3070 (this has been changed midway so stayed the same in new configuration waiting for serie 50xx)
RAM 2x8 corsair vengeance ddr4
AIO arctic liquid freezer 240 (not 100% sure on this one sorry but reasonably so)
SSD can't remember sorry, just that it was 512 gb and not the nvme version
CORSAIR RM 750w 80+
1 rear fan included with case (can't remember model)
2 front fan added in front (can't remember anything about those)
CASE again can't remember

You forgot to mention the make and model of your case. Fans came bundled with the case or did you go for aftermarket options?
You're right sorry.
Case is a MSI vampiric 010x. The rear fan is the case specific one. The 3 front ones i ordered them separately but, maybe in a not that smart way, i didn't specify anything to my retailer other than them to be 120mm so that they could fit the case, and i didn't really bother to check for model later. If it's really that important to know them (considering the cpu fan readings showing that behaviour belongs to the AIO) i guess i could check in the case if i can find the model without having to dismantle too much, otherwise i can phone my retailer and ask but that has to wait till monday.

Oh i forgot to mention that BIOS and motherboard firmware are both updated to the latest version (oct 9th 2024) same goes for driver and even Windows

Haw's AIO cooler connected to MB, Ideally, only radiator fans to CPU_FAN connector on the MB. Pump on those Arctic cooler is not speed adjustable nor it reports RPM. so it can be connected on any MB header and will work full speed. Pump or radiator fans should not be connected with any other fans or thru 3rd party controllers.
When radiator fans are connected properly to CPU_FAN header, make sure it's set to PWM and not DC control mode. After that, you can set fan speed curve in BIOS which may also include up/down delay.

 

[pinocammino]

I did some digging in the bios under the fan monitoring and this is how i found out fans are set up right now

CPU1 can be PWM DC or AUTO currently set on AUTO with smart fan mode turned on
Curve looks like this:

0° 2,40v
45° 4,20v
65° 8,40v
80° 12,00v

temp values taken from CPU
step up and step down time both set at 0.1s

PUMP 1 can be PWM or DC currently set to PWM with smart fan disabled

35° 50%
40° 70%
70° 90%
90° 100%

temp values taken from CPU
step ap and step down time both set at 0.1s

All the other sys fan are set to DC with a fixed value, no curve at all.

Note that i didn't set any of those curves (frankly i have no experience setting a fan curve so i don't even know if they look fine), and have been probably set to that by default with the bios update i did.

As i wrote before, monitoring the fans shows that CPU fan keeps spiking between 0 and 1300ish rpm on idle every second or so, and correctly ramps up during stress test based on CPU temp, while PUMP 1 fan, despite having a curve in bios, is always going at around 2000 RPM (there's like a 40 rpm variance between min and max), no matter if pc is idling, working or doing a stress test.
All the other sys fan, as expected by not having a curve but just a fixed value, are always working at the same speed.

Also CountMike forgive me if i've misunderstood you (english isn't my first language) but since i saw you mentioning the Arctic cooler, that was my old one that i only mentioned cause Lutfij asked me about my old configuration too. My question is related to the new one that is the MSI MAG coreliquid m240.

 

[pinocammino]

After comparing the values i wrote above with the specifications from MSI documentations i noticed there was something wrong with the speed of the components. Supposedly the pump speed at 100% should be at 3100 rpm and not 2000 like it was showing in readings, while the radiator fans (CPU 1 FAN) are supposed to go at 2000 RPM maximum but during stress tests they were reaching values in the 2800 range.
That made me realize that maybe the pump and cpu fan connectors were inverted so i dismantled the AIO to check the connections and that was in fact the case. The problem with the erratic behaviour was that while the radiator fans have a 4 pin connector, thus supporting PWM, the pump has a 3 pin one so the curves set in bios weren't working properly cause they were trying to control the wrong component.
After switching the connectors to the correct positions, the readings seem more coherent: now the CPU 1 FAN is stable at around 800ish RPM on idle, PUMP 1 is stable at 3100 RPM no matter what, and ofc all the other case fans haven't been changed since before.
This also had the side effect that the fans are quieter and the idle temp 1-2 degrees cooler.

So, while the original problem seems to be solved, i now need help with setting up a proper fan curve.
Currently going with the one bios set by itself that is

0° 20%
45° 35%
65° 70%
80° 100%

temp source CPU
step up and down both 0,1s

Ofc i understand that you can't give me exact values for the curve cause that really varies case by case depending on proper airflow but i'd be grateful on insights for the target value i should look for the cpu temp to be, considering also that fan noise is not that big of an issue so i don't mind it being more noisy if it keeps the cpu cooler.

As a final note for moderators: i don't know if it's proper to keep using this thread for this reason or if it's better to mark this one as solved and open a new one for the help on fan curve request. Just let me know