CPU temp increasing and CPU fan slowing down if case fan is added

Toggle sidebar Toggle sidebar
B

bursuq

Reputable
Dec 9, 2014
5
0
4,520
I have a stock cooled FX-8350. After adding an exhaust fan on the top side of my case i noticed a consistent increase in CPU temperature. After checking fan speeds while running Prime95 i noticed that the temperature increase on the CPU is caused by the CPU fan not speeding up. It sticks at around 3300 rpm, but if i remove the case fan it goes up to 4500 rpm. The case fan is a few centimetres away from the CPU's heatsink and cooler.
Isn't CPU fan speed a function of the CPU's temperature (both core and socket temps increase consistently when case fan is added)? How can the case fan disrupt the CPU fan's speed?

Thanks
 
Solution
B
Yeah, so no matter what i do, if case fans are spinning the CPU fan will not go into high speed. I think i can't control it fully e.g. i set it to 100% PWM it il spin up to ~3300rpm. However as i mentioned before if case fans are turned off it will go up to 4500 rpm for 100% PWM. I think there is some sort of "turbo" mode for the CPU fan.
It is actually pretty funny if i think about it. Here are two tests i performed:
1)prime 95 running, case fans running: cpu temp ~73 deg, cpu fan 3300 rpm
2)i put a large book on top op my case completely covering my case's top exhaust, trapping hot air inside the case: cpu temp ~65 deg, cpu fan rpm 4500
I think they(gigabyte) tried to do something smart here with the cpu fan speed, by they didn't...
Sort by date Sort by votes
A

APassingMe

Reputable
Aug 25, 2014
613
0
5,160
The speed of your CPU fan is controlled by your motherboard, you should have some settings in the bios to adjust it. You might have your CPU fan plugged into the port for the case fan instead of the port for the CPU fan, that would explain your symptoms but you should of had an error beep so that's probably not the case unless you have something else plugged into the CPU fan port.

Anyway, go ahead and check the ports to make sure you have them right and check the bios settings for fan control.
 
Upvote 0 Downvote
B

bursuq

Reputable
Dec 9, 2014
5
0
4,520
CPU fan is plugged into the correct port on the main board, and the BIOS settings for CPU fan are set to automatic control. Also the air flow in my case is correct. The issue occurs regardless of where i plug the case fan (molex or SYS_FAN on MB).
I think the only explanation is that physical proximity between case fan and CPU fan is causing the CPU fan to stay at lower speeds.
I'll try to change the bios setting for CPU fan speed to manual (my MB has an option to set a degrees to PWM ratio e.g. 1.5% PWM per degree) and see what happens.
 
Upvote 0 Downvote
A

APassingMe

Reputable
Aug 25, 2014
613
0
5,160
It could be some weird settings in the "automatic control" program... which you wouldn't be able to do anything about unless they fix it in a firmware update. Go with the manual control, stock CPU fans don't get too loud.
 
Upvote 0 Downvote
A

APassingMe

Reputable
Aug 25, 2014
613
0
5,160
Oh, I forgot about this but sometimes adding another fan to the case will actually increase case temperature in spots... just something to keep in mind. The CPU fan should of spun up automatically though...
 
Upvote 0 Downvote
B

bursuq

Reputable
Dec 9, 2014
5
0
4,520
Yeah, so no matter what i do, if case fans are spinning the CPU fan will not go into high speed. I think i can't control it fully e.g. i set it to 100% PWM it il spin up to ~3300rpm. However as i mentioned before if case fans are turned off it will go up to 4500 rpm for 100% PWM. I think there is some sort of "turbo" mode for the CPU fan.
It is actually pretty funny if i think about it. Here are two tests i performed:
1)prime 95 running, case fans running: cpu temp ~73 deg, cpu fan 3300 rpm
2)i put a large book on top op my case completely covering my case's top exhaust, trapping hot air inside the case: cpu temp ~65 deg, cpu fan rpm 4500
I think they(gigabyte) tried to do something smart here with the cpu fan speed, by they didn't quite think it through.
 
Upvote 0 Downvote
Solution
A

APassingMe

Reputable
Aug 25, 2014
613
0
5,160
Sounds like a gigabyte support problem, you could try contacting them. It's possible that there's a bug in the firmware, make sure you check for new firmware and read the update post on them. You can also disable the CPU fan port on the MB and replace it with an adapter but that's kind of messy.
 
Upvote 0 Downvote
You must log in or register to reply here.

TRENDING THREADS

Latest posts

Moderators online

Share this page

COMPANY
RESOURCES
FOLLOW
Top Bottom