[SOLVED] CPU temp 20+ degrees LOWER in BIOS compared to OS

[MemeMan69]

I've been fiddling with my fan speed curves to stop my CPU fan from buzzing so loudly and noticed something.

When adjusting speeds in the System Info Viewer the CPU will vary from around 65-75 degrees C. When I go into the BIOS however it will almost always hover around 40-42 degrees C. CPU always idles at 60+ degrees in the operating system, even with nothing open/nothing running.

From what I've seen elsewhere online its more typical to have slightly higher temps in the BIOS, rather than lower. Is this still the case? What could a possible reason be for this? Whenever I boot up anything the CPU think its running at 85+ degrees (or maybe it is?) and the fans whirr up to 100% and annoy the hell out of me.

For what its worth, the PC is not a new build. Had it for a couple of years but only started getting annoyed by the fans after I moved it from below my desk to next to my desk (ironically, to improve airflow and reduce internal temps).
Ryzen 5 3600 (stock cooler) with a B450 AORUS Elite

 

[Lutfij]

Welcome to the forums, newcomer!

When posting a thread of troubleshooting nature, it's customary to include your full system's specs. Please list the specs to your build like so:
CPU:
CPU cooler:
Motherboard:
Ram:
SSD/HDD:
GPU:
PSU:
Chassis:
OS:
Monitor:
might want to also include the fans in your case and how they're oriented.

Another thing to note, off the top of my head you should be in the mid to high 30(Deg C)'s with that processor, not the 60's.

 

[CountMike]

I've been fiddling with my fan speed curves to stop my CPU fan from buzzing so loudly and noticed something.

When adjusting speeds in the System Info Viewer the CPU will vary from around 65-75 degrees C. When I go into the BIOS however it will almost always hover around 40-42 degrees C. CPU always idles at 60+ degrees in the operating system, even with nothing open/nothing running.

From what I've seen elsewhere online its more typical to have slightly higher temps in the BIOS, rather than lower. Is this still the case? What could a possible reason be for this? Whenever I boot up anything the CPU think its running at 85+ degrees (or maybe it is?) and the fans whirr up to 100% and annoy the hell out of me.

For what its worth, the PC is not a new build. Had it for a couple of years but only started getting annoyed by the fans after I moved it from below my desk to next to my desk (ironically, to improve airflow and reduce internal temps).
Ryzen 5 3600 (stock cooler) with a B450 AORUS Elite

While in BIOS/UEFI there's low load but power saving features are not used either Unless it's excessive it's not even important. If it's not changing it is most probably locked to what reading it had at moment in post,
Once booted to OS there's certain load which changes conditions from (relative) idle to full load on one, few or all cores, Voltages and fans are also regulated etc.

 

[hotaru.hino]

When you're in UEFI/BIOS the CPU will be constantly running at base clock speeds and is not going to be put into a low power state. This is why you see people say it runs warmer in UEFI/BIOS because the CPU won't go into lower power state. The reason why UEFI/BIOS doesn't do this is:

• Keeps the code simpler
• Makes sure that the CPU is configured for its base clock speed, which suggests that at the bare minimum it's working
• Useful as a sanity test for cooling (if the CPU temps are too high for comfort, you know there's something wrong with the cooler)

However in the flip side of things, in the OS, the CPU is allowed to turbo boost, which in Ryzen processors if a core is boosting, will always make it look like the CPU is hot. This is because Ryzen CPUs report the hottest thing as the CPU temperature, even though the entire processor may be hovering at a much lower temperature.

If you want to see if boosting is causing the system to idle at a higher temperature, then do the following:

• Open a command prompt as an administrator
• Type in powercfg -attributes sub_processor perfboostmode -attrib_hide
• Open the Start Menu and in the search bar, type in "Edit power plan"
• Click on "Change advanced power settings"
• In the pop-up window, go to "Processor power management" -> "Processor performance boost mode" -> set the "Setting" to "Disabled"

You should see the CPU is now limited to the base clock speed.

 

[MemeMan69]

When you're in UEFI/BIOS the CPU will be constantly running at base clock speeds and is not going to be put into a low power state. This is why you see people say it runs warmer in UEFI/BIOS because the CPU won't go into lower power state. The reason why UEFI/BIOS doesn't do this is:

• Keeps the code simpler
• Makes sure that the CPU is configured for its base clock speed, which suggests that at the bare minimum it's working
• Useful as a sanity test for cooling (if the CPU temps are too high for comfort, you know there's something wrong with the cooler)

However in the flip side of things, in the OS, the CPU is allowed to turbo boost, which in Ryzen processors if a core is boosting, will always make it look like the CPU is hot. This is because Ryzen CPUs report the hottest thing as the CPU temperature, even though the entire processor may be hovering at a much lower temperature.

If you want to see if boosting is causing the system to idle at a higher temperature, then do the following:

• Open a command prompt as an administrator
• Type in powercfg -attributes sub_processor perfboostmode -attrib_hide
• Open the Start Menu and in the search bar, type in "Edit power plan"
• Click on "Change advanced power settings"
• In the pop-up window, go to "Processor power management" -> "Processor performance boost mode" -> set the "Setting" to "Disabled"

You should see the CPU is now limited to the base clock speed.

Thanks for the reply. This seems to be a big contributing factor. Was set to 'aggressive'. Disabling lowered the idle temp by a good 15-20 degrees.

I wonder if there is anything that can be done about this? Seems like it shouldn't be trying to boost when sitting idle. Could it be a deeper issue or is this just a feature of the chip? There is no noticeable difference in temps with any other setting (enabled, aggressive, efficient enabled, efficient aggressive, aggressive at guaranteed, efficient aggressive at guaranteed)

 

[hotaru.hino]

I wonder if there is anything that can be done about this? Seems like it shouldn't be trying to boost when sitting idle. Could it be a deeper issue or is this just a feature of the chip? There is no noticeable difference in temps with any other setting (enabled, aggressive, efficient enabled, efficient aggressive, aggressive at guaranteed, efficient aggressive at guaranteed)

Typically what you'd see with Ryzen processors is a periodic spiking of temperatures. There's still tasks to do while idling, but Windows will tend to clump them up all at once and send it to 1-2 cores for processing, which causes those cores to boost hard. If the temperatures aren't dropping while idling, it could mean there's something always firing off.

 

[Firestone]

You might be interested in setting your CPU to Eco Mode in your BIOS as well. Reduces boost speeds but also puts cores to sleep more aggressively.