[SOLVED] Fans continually cycling between fast and faster

[AJAshinoff]

In a windows 2019 server, using a Enermax platnimax 1200w power supply, I have 4 case fans (back plane cooling), a slot cooling card (2 fans), 2 additional rear facing case fans, and the CPU fan.

It runs great. Still, from the day I built this system I can hear the fan(s) continuously cycling from fast to faster and back again. The system is not hot and I don't see any component approaching a heat threshold. I've checked the BIOS and windows power setting and found nothing that would indicate energy conservation measures.

Has anyone experienced this? Could this be a bad power supply?

 

[hotaru.hino]

What are the rest of the system specs?

My gut feeling the CPU is simply hitting turbo and fan speed curve is reading off the hottest part of the CPU rather than say an average or whatnot.

 

[AJAshinoff]

What are the rest of the system specs?

My gut feeling the CPU is simply hitting turbo and fan speed curve is reading off the hottest part of the CPU rather than say an average or whatnot.

Thanks! I didn't consider that. What is your suggestion? A new heat sync/fan? Ensuring nothing in the BIOS is overworking the CPU?

 

[hotaru.hino]

Thanks! I didn't consider that. What is your suggestion? A new heat sync/fan? Ensuring nothing in the BIOS is overworking the CPU?

The only suggestion I have is to figure out where the CPU tends to loiter around and adjust your fan curve based on that.

The problem is no matter what you do, if the fans are going off the hottest part of the CPU, the core that's turbo boosting is going to spike regularly. So no matter how beefy of a cooling system you'll get, short of something like phase-change or LN2, you'll have a regular spike in temperature.

Also BIOS will keep the CPU at base frequencies. This is for sanity checking purposes. And to keep the BIOS lean.

 

[AJAshinoff]

You hit the nail on the head! I revisited the BIOS and looked specifically at the CPU power settings. There were several power saving management features turned on. After turning them off and rebooting the server the fans are now consistent rather than speeding up and slowing down.

For good measure, I also reversed one of the back panel fans so its blowing directly on the CPU heat sink.

My server room is a constant 68 degrees, far cooler than my office. Once this server gets back to its rack space what little heat there is coming off the CPU should be offset.

Thank you! This matter was nothing critical, more of a annoyance knowing, but I've been thinking on this too long and its good to put it to rest. Thanks again!