Z97 Extreme 3 has bugged CPU FAN control

donger wrote: I setup in bios so when my CPU gets hotter the fan is spinning quicker. This works very well 95% of the time and the tempearture nexer exceeds 80*. But sometimes the fan gets stuck @ 20% like the motherboard can't read CPU temperature properly or something and the fan gets stuck on 20% speed. This causes the cpu to overheat and eventually windows crashes. Please help me with the issue. I have new bios.

Not much information in your post, so questions first.

Have you tried clearing the BIOS/CMOS?

How long have you been having this problem? Is this a new PC build with the issue from the start, or has the PC been fine and the problem began recently?

What CPU and CPU cooler are you using? If it is not the stock Intel CPU cooler, is the fan connection a three pin or four pin connector? Which fan header is it connected to?

What are you using to monitor the CPU cooler's fan speed, and CPU temperature?

The default CPU fan speed profile will change the CPU cooler's fan speed as the CPU gets warmer. But you've configured it yourself in the UEFI/BIOS? That's fine, but what fan speed profile did you select, or is it a custom profile?

If you updated the BIOS, all the BIOS options are reset to their default values. If you created a custom profile, or selected a different built in profile, you'll need to configure that again in the BIOS.

If the CPU were to over heat, the CPU shuts itself off, or the board shuts down, to protect the CPU. Windows crashing is not what happens when a CPU overheats, since the PC will just restart again when Windows crashes. So what exactly happens when you say the CPU overheats and "Windows crashes"?

Have you opened the PC case recently to check if the CPU cooler and its fan are clean and free of dust? Even if the CPU cooler's fan was running at a low speed, the CPU would need to be under a heavier load to overheat. But if you are using the stock Intel CPU cooler, that is more likely to happen.

so any help? unfortunately my warranty is over so i can't RMA the mobo

donger wrote: so any help? unfortunately my warranty is over so i can't RMA the mobo

Your main problem is using a three pin fan on the CPU_FAN2 header only, and no four pin fan on the CPU_FAN1 header. The CPU_FAN2 connector is really a secondary connector for CPU coolers that use two fans, like some Noctua models.

I'd like to know which model Enermax fan you are using, since the Enermax fans I've used have been not good at all. Quiet but low maximum RPM.

How are you able to "touch the heat spreader" on a CPU that is under a CPU cooler? If you are talking about the CPU cooler itself that is at 80C, then that fan is defective or running as such a low speed that its doing nothing. Some people run Megahalems passive, meaning no fan on them at all, just case fans pushing air in and out of the case. There is no way a Megahalems is at 80C, even without a fan.

I'd like to see the CPU_FAN2 speed in a screen shot of the HW Monitoring screen, as well as the CPU temperature. If it is much below 1,000RPM, then it needs adjustment of the fan speed percentage at a lower temperature. But we don't know what model fan it is, so no idea of its specs.

All PC fans are different, there are no standards for fan speed at a specific voltage. The maximum speed of various 120mm fan models can be 800RPM or less, up to over 3,000RPM. So the fan speed control percentage must be adjusted for each fan model. The default values are just an average for some fans, but won't work well with all fans.

If the fan is barely working, you need to adjust the percentage values higher at lower temperatures. But a good four pin PWM fan on the CPU_FAN1 header is really what you need. I doubt there is anything wrong with the board, or nothing that loading the UEFI/BIOS defaults, or even flashing the UEFI over again if it was corrupted, would not fix.

Also, no idea about any chassis fans in the PC case, or what case you are using. You must have cool air coming in, and exhausting heated air out of the case, particularly when using a video card and gaming.

boombastik wrote: But if i disable cms in uefi ( pure uefi), this dont happen, so maybe if u have the cms compatibilty to on , it brakes the initialization of fan.(random times)

Edited by donger - 12 Oct 2017 at 5:25am

Ok i set it to ultra boot now, was fast boot before. Unfortunately i never had any monitoring software ON when the crashes happened. All i know that after the crash, on the bluescreen, i open the case see the fan is spinning molasses like like and the megahalems is so hot i can't touch it. After i reset the PC the fan goes to 100% right away to cool down the CPU.