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System temperature increases when rear fan is added

Last response: in CPUs
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July 13, 2012 4:01:20 PM

I recentle bought the 8cm fan for my CPU. I find this strange that the system temperature rises as the fan is on! It's at the rear of the CPU(exhaust,outtake). Right now the system temperature is 26ºC (78ºF)(min 25ºC (76ºF), max 28ºC (82ºF)) but when i use the rear fan it raises to 40ºC-45ºC! Is this a bad temperature sensor or the fan?
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July 13, 2012 4:07:47 PM

It all depends on the air flow within the case....simply adding a Fan doens't guarantee more air flow over the CPU heatsink. :) 

Most probably your rear fan is directly throwing out the incoming fresh air without letting it pass over the CPU heatsink :) 
Open the case and try to imagine the direction in which air in drawn in/expelled from each of the vents.....then reposition your fan at a approraite location :)  cheers :) 
July 13, 2012 4:35:40 PM

i tried almost all possible ways! putting the fan at the back(intake and outtake) on the side cover(intake and outtake) but still nothing! :(  there's no slots at the front though!
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July 13, 2012 4:51:52 PM

What's ur CPU temp's under full load on all cores?? Stress it with something like Prime95 .
If its less than 70C, then throw away d fan, and don't bother :D 
July 15, 2012 2:54:47 AM

I would think you are blowing the CPU hot air on to the sensor that is why it goes up. Reverse the fan so it blows the other way.
Other wise you are just blowing the hot air inside the case and it can not get out so the temps of the sensor on the MB all go up
July 21, 2012 6:48:42 AM

Rainey said:
I would think you are blowing the CPU hot air on to the sensor that is why it goes up. Reverse the fan so it blows the other way.
Other wise you are just blowing the hot air inside the case and it can not get out so the temps of the sensor on the MB all go up

No! I tried all possible ways...intake and outtake both on side and at the back of my cpu, yet the temperature keeps increasing! I'm starting to think its a bad temp sensor! :/ 
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July 21, 2012 7:22:57 AM

Can u post a picture of your open case?
July 21, 2012 11:31:01 AM

Is hard to imagine an 80x80 fan for a cpu cooler also i quess this cpu cooler blowing the air vertical to the motherboard?

We need more infos about your cpu coller, pc case exoust fans, motherboard, graphics card, hard disks.

A good Thermal analysis I made here, 1st post, simply because the op gave all the details we needed to know in order to jump into a safe conclusion:

http://www.tomshardware.co.uk/forum/340000-10-corei-792...

PS For what is worth my opinion is the vertical blowing cpu coolers that spreading the heat all over the motherboard components are bankrupt, even the traditional pc boxes are bankrup, the feature belongs in top to bottom pc cases for sure.
July 21, 2012 5:10:26 PM

MegaBlaze007 said:
No! I tried all possible ways...intake and outtake both on side and at the back of my cpu, yet the temperature keeps increasing! I'm starting to think its a bad temp sensor! :/ 


If you are putting the fan on the CPU heat sink then you are just filling the case with the CPU's hot air and it is not cooling anything down. My CPU heat sink has a fan and it points out the back of the case where there is a case fan that removes the hot air from the case.

I agree with Giatrakis, you need to post some more info or pictures because it is not clear where you are putting the fan or what kind of heat sink or case you have.
July 24, 2012 9:13:23 AM

thank you all but i prefer not to use the fan! lol
!