PSU fan keeps turning on and off at idle

AusWolf · Oct 31, 2022

Hi guys,

I have a Seasonic Prime GX-750 (750 W Gold) in my main rig. I've noticed that its fan keeps turning on and off when the system is idle. I know this because it gives a very quiet, but audible rattle when it starts up, which I don't hear when I turn off its fan stop feature. According to the official website, the fan shouldn't turn on below 300 W power consumed by the PC and there is no way my system eats that much at idle (specs in my profile). There must be something else triggering the fan to turn on and off, but what? Maybe temperature? Or is it faulty?

Any ideas?

cvaldes · Oct 31, 2022

We can start with two basic questions:

What are the loads on the CPU and GPU at idle?
What is the internal temperature of the case at idle?

AusWolf · Oct 31, 2022

cvaldes said:
We can start with two basic questions:

What are the loads on the CPU and GPU at idle?

What is the internal temperature of the case at idle?

CPU around 1-3%, GPU around 0-1%. According to HWInfo, the CPU eats about 9-12 Watts, the GPU 8-9 Watts.
That's a good question. The PSU is housed in a separate compartment with its own "breathing holes" but no direct airflow. Are Seasonic PSU fans triggered also by temperature besides power?

Udyr · Oct 31, 2022

Are Seasonic PSU fans triggered also by temperature besides power?

The majority, if not all, are triggered by temperature, not the power being drawn.

If it's not the overall temperature of the case or the PSU, then your unit might have a faulty temp sensor, which is triggering the auto fan function. I'd recommend leaving the fan on all the time if there's a button to do so.

AusWolf · Oct 31, 2022

Udyr said:
The majority, if not all, are triggered by temperature, not the power being drawn.

If it's not the overall temperature of the case or the PSU, then your unit might have a faulty temp sensor, which is triggering the auto fan function. I'd recommend leaving the fan on all the time if there's a button to do so.

If that's the case, then it might be internal temps in the PSU. I don't hear the fan turn on straight after a cold start - some time has to pass before it starts doing it.

As I mentioned, there is no airflow pointing at it because it sits in its own compartment within the case, so its internals might just get warm enough for the fan to turn on even at idle. Maybe I'll have to test this theory with another fan pointing at it, but for now, I'll just leave the fan on at all times as you said.

3x0 · Oct 31, 2022

To my knowledge, Seasonic PSUs are configured to turn on the fan based on either the power draw or temperature.

REdebb · Oct 31, 2022

Nothing to worry about its doing what its supposed to do lol if its turning on that is because it is hitting its threshold it will be based on TDP so it knows exactly when it need to turn on it also won't be 40% of 750w either it will be 40% out of 100c because we are talking about themals not watts even though there is correlation between to two.

EDIT:
Sorry i kind of said that incorrectly it will be TDP based so a fulcrum point where the two meet thermodynamics and watts when the PSU gets to that point it turns the fan on, if the fan is on its because it needs to be on.

The only time i would be concerned is if it switched constantly while doing nothing on the PC.

Shrek · Oct 31, 2022

AusWolf said:
As I mentioned, there is no airflow pointing at it because it sits in its own compartment within the case

Is there a way to fix that? if it has just a little wind from the case fans, it would probably be fine at idle.

shovenose · Oct 31, 2022

If possible just turn off hybrid fan feature so the fan runs at minimum all the time. I know both my Seasonic-platform Phanteks and my CWT Thermaltake have switched to make the fan run all the time.

AusWolf · Nov 1, 2022

Shrek said:
Is there a way to fix that? if it has just a little wind from the case fans, it would probably be fine at idle.

Not in this case, no.

It sits right next to the back wall of the case with its own breathing holes (Corsair 280X).

REdebb said:
The only time i would be concerned is if it switched constantly while doing nothing on the PC.

That's exactly what's happening.

doyll · Nov 2, 2022

When was last time you cleaned case filters and/or blew out PSU?
It's possible that dust/lint in grill mesh / filter mesh is restricting airflow causing fan to kick on to meet airflow demands.

System Name	Nebulon-B Mk. 4
Processor	AMD Ryzen 7 7800X3D
Motherboard	MSi PRO B650M-A WiFi
Cooling	be quiet! Dark Rock 4
Memory	2x 24 GB Corsair Vengeance EXPO DDR5-6000
Video Card(s)	Sapphire Pulse Radeon RX 7800 XT
Storage	2 TB Corsair MP600 GS, 2 TB Corsair MP600 R2, 4 + 8 TB Seagate Barracuda 3.5"
Display(s)	Dell S3422DWG, 7" Waveshare touchscreen
Case	Kolink Citadel Mesh black
Power Supply	Seasonic Prime GX-750
Mouse	Logitech MX Master 2S
Keyboard	Logitech G413 SE
Software	Windows 10 Pro
Benchmark Scores	Cinebench R23 single-core: 1,800, multi-core: 18,000. Superposition 1080p Extreme: 9,900.

System Name	daily driver Mac mini M2 Pro
Processor	Apple Silicon M2 Pro (6 p-cores, 4 e-cores)
Motherboard	Apple proprietary
Cooling	Apple proprietary
Memory	Apple proprietary 16GB LPDDR5 unified memory
Video Card(s)	Apple Silicon M2 Pro (16-core GPU)
Storage	Apple proprietary 512GB SSD + various external HDDs
Display(s)	LG 27UL850W (4K@60Hz IPS)
Case	Apple proprietary
Audio Device(s)	Apple proprietary
Power Supply	Apple proprietary
Mouse	Apple Magic Trackpad 2
Keyboard	Keychron K1 tenkeyless (Gateron Reds)
Software	macOS Ventura 13.6 (including latest patches)
Benchmark Scores	(My Windows daily driver is a Beelink Mini S12. I'm not interested in benchmarking.)

System Name	Nebulon-B Mk. 4
Processor	AMD Ryzen 7 7800X3D
Motherboard	MSi PRO B650M-A WiFi
Cooling	be quiet! Dark Rock 4
Memory	2x 24 GB Corsair Vengeance EXPO DDR5-6000
Video Card(s)	Sapphire Pulse Radeon RX 7800 XT
Storage	2 TB Corsair MP600 GS, 2 TB Corsair MP600 R2, 4 + 8 TB Seagate Barracuda 3.5"
Display(s)	Dell S3422DWG, 7" Waveshare touchscreen
Case	Kolink Citadel Mesh black
Power Supply	Seasonic Prime GX-750
Mouse	Logitech MX Master 2S
Keyboard	Logitech G413 SE
Software	Windows 10 Pro
Benchmark Scores	Cinebench R23 single-core: 1,800, multi-core: 18,000. Superposition 1080p Extreme: 9,900.

System Name	Back in Black
Processor	Ryzen 5 3600
Motherboard	MSI B450 Tomahawk
Cooling	ID-Cooling SE-224-XT Black
Memory	Corsair Vengeance LPX 16GB (2x8) 3000mhz C15
Video Card(s)	Asus Rog Strix GTX 1070 TI Advanced Edition
Storage	Crucial MX500 500GB / Solidigm P41 Plus 1TB
Display(s)	Samsung 32" TV 1080p
Case	Montech Air X Black
Power Supply	Thermaltake Toughpower GF1 750W Gold
Mouse	Redragon M711 Cobra
Keyboard	Corsair K55

System Name	Nebulon-B Mk. 4
Processor	AMD Ryzen 7 7800X3D
Motherboard	MSi PRO B650M-A WiFi
Cooling	be quiet! Dark Rock 4
Memory	2x 24 GB Corsair Vengeance EXPO DDR5-6000
Video Card(s)	Sapphire Pulse Radeon RX 7800 XT
Storage	2 TB Corsair MP600 GS, 2 TB Corsair MP600 R2, 4 + 8 TB Seagate Barracuda 3.5"
Display(s)	Dell S3422DWG, 7" Waveshare touchscreen
Case	Kolink Citadel Mesh black
Power Supply	Seasonic Prime GX-750
Mouse	Logitech MX Master 2S
Keyboard	Logitech G413 SE
Software	Windows 10 Pro
Benchmark Scores	Cinebench R23 single-core: 1,800, multi-core: 18,000. Superposition 1080p Extreme: 9,900.

Processor	AMD Ryzen 7 5800X3D
Motherboard	MSI MPG B550I Gaming Edge Wi-Fi ITX
Cooling	Scythe Fuma 2 rev. B Noctua NF-A12x25 Edition
Memory	2x16GiB G.Skill TridentZ DDR4 3200Mb/s CL14 F4-3200C14D-32GTZKW
Video Card(s)	PowerColor Radeon RX7800 XT Hellhound 16GiB
Storage	Western Digital Black SN850 WDS100T1X0E-00AFY0 1TiB, Western Digital Blue 3D WDS200T2B0A 2TiB
Display(s)	Dell G2724D 27" IPS 1440P 165Hz, ASUS VG259QM 25” IPS 1080P 240Hz
Case	Cooler Master NR200P ITX
Audio Device(s)	Altec Lansing 220, HyperX Cloud II
Power Supply	Corsair SF750 Platinum 750W SFX
Mouse	Lamzu Atlantis Mini Wireless
Keyboard	HyperX Alloy Origins Aqua

System Name	HP Compaq 8000 Elite CMT
Processor	Intel Core 2 Quad Q9550
Motherboard	Hewlett-Packard 3647h
Memory	16GB DDR3
Video Card(s)	Asus NVIDIA GeForce GT 1030 2GB GDDR5 (fan-less)
Storage	2TB Micron SATA SSD; 2TB Seagate Firecuda 3.5" HDD
Display(s)	Dell P2416D (2560 x 1440)
Power Supply	12V HP proprietary
Software	Windows 10 Pro 64-bit

System Name	Sierra ~ Server
Processor	Core i5-11600K ~ Core i3-12100
Motherboard	Asus Prime B560M-A AC ~ MSI PRO B760M-P
Cooling	CM 212 Black RGB Edition ~ Intel Stock Cooler
Memory	64GB (2x 32GB) DDR4-3600 ~ 32GB (4x 8GB) DDR4-3200
Video Card(s)	XFX Radeon RX 6950 XT ~ EVGA GeForce GTX 970
Storage	4TB Samsung 990 Pro with Heatsink NVMe SSD ~ 2TB Kingston NV1 NVMe SSD + 500GB WD Blue SATA SSD
Display(s)	2x Dell S2721QS 4K 60Hz ~ N/A
Case	Asus Prime AP201 - Open Frame Chassis
Power Supply	Thermaltake GF1 850W ~ Thermaltake Smart 500W
Software	Windows 11 Pro ~ Proxmox VE
Benchmark Scores	Laptops: Dell Latitude E7270, Dell Latitude 14 Rugged 5420.

PSU fan keeps turning on and off at idle

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