# CPU and how to reverse fan direction in bios?



## Hunteil (Mar 30, 2007)

Hi, I have purchased a 3.4 Intel processor that came with a really nice fan assembly... MFG Part #: C91968-001 Intel Socket 775 Heat Sink and Fan up to 3.8GHz

This fan is nice and easy to attach to the board but it blows air away from the heatsink...

using the Intel Temp detector, at idle the temp is 30-35C and at watching a movie it's 50-60C and playing war craft 3 it's 65-75C and then the Intel program jumps in and warns me and kicks me out of the game to the desktop....quite helpful really. But now I'm a bit lost...

I have the power supply blowing out, the back fan being 4x4" blowing in on the processor, lower fan in bottom left corner blowing out. I have the side window blowing air in, and the right right i have my hard drive with a fan attached to it's top blowing lots of air out the front... I also have a 4x4 in the bottom right hand blowing air in.... i can't mechanically reverse my CPU fan.....is there a way to reverse it's fan direction in BIOS or somewhere in the system? I have a good air flow I thought but maybe i'm missing something.


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## 95five-0 (Dec 7, 2004)

The air should always pull away from the cpu. Also proper air flow should be suck in from the front and blow out the rear. If you have too many fans blowing different directions it could hurt your cooling.


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## Tumbleweed36 (May 14, 2005)

_*Suggested Fan Placement and Cooling*_

> CPU/Heatsink fan blowing down on heatsink

> Fan in front of case pulling in cool air

> Fan in rear of case pulling hot air out of the case and blowing out the back

> Fan on top pulling warm air out of the case (heat rises)

> Most instances, side case fans pulling cool air into the case with the exception of any very near the top of the case to take advantage of the hot air rises scenario.

> Smooth air flow front to back in case

Other Considerations:

> Move ribbon cables out of the air flow area if possible

> Suggest round IDE cables for best air flow

Post back with questions/concerns.

Note: If you simply unsnap or unclamp the heatsink fan, you can simply turn the fan upside down and it will blow the other way. Easy job, but don't disturb the heatsink that is on the CPU or you will have to redo the Artic Silver thermal paste.


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## Hunteil (Mar 30, 2007)

Okay I hope you can understand the top picture i drew using ... 
The arrows are the direction the air flows from the fan.... the + is air blowing towards you and the X is air blowing from you into the case.

Every darn hole is taken up for fans... i have reversed fan in the back 4x4 and no difference. I even proped up the case to allow more air flow into the front bottem and I've seen a little help with that. The top right fan is a DataStor USCTXX 5.25" Dual Fan System Cooling Tray. This thing forces lots of air out.
very nice....

Everywhere I looked i found people saying that pulling air into the heatsink and letting it dispears that way is a way better solution.... so which is it?


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## Tumbleweed36 (May 14, 2005)

You don't have to have every fan I listed. Just that you need to have those in the case blowing the direction I listed. The heatsink fan needs to blow down in most cases. If you have a baffle from the fan to the outside of the case, then there are times that you can pull air off there and have it work. However, you can also use that baffle to pull in cool air, so I just never have it pulling air up regardless. 

About 90% or more of computer techs and CPU manufacturer's will tell you that you need to blow down on the heatsink. There is a percentage that will disagree and that doesn't make them wrong, just that they see it differently and we need to respect that opinion.

Bottom line, heatsink fan blowing down, back fan pulling hot air OUT of case, front fan pulling cool air in......those are almost a necessity with this CPU. You might want also to redo your thermal paste as per the Artic Silver instructions in my signature. That should keep you cool enough even in the games. Your temps are not that bad with this CPU until you play the last game you listed. So, if you make some alternations, it should work for you.


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## Hunteil (Mar 30, 2007)

the fan structure is this: http://www.geeks.com/details.asp?invtid=C91968-001&cat=FAN

As you can see i can remove the fan but i can't flip it over....so is there a way to go into BIOS / software and switch the fan direction? so should i buy a new one? I saddly can't figure out how to tell if a CPU fan blows and pulls air b/c the fins look the same.


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## mattlock (Dec 28, 2005)

Unfortunately, you can not reverse the fan direction from the bios.


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## Hunteil (Mar 30, 2007)

if i would cut a hole in front of the CPU fan in the side wall of the computer case and put a funnel in to it and guide the air out from the CPU, would that help? or cutting the plexy glass on the side of the case just not worth it?


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## Deleted090308 (Jan 25, 2007)

You could cut the + and - wires between the fan and mobo - then connect + from the fan to - from the mobo and vice versa (that will make the fan blow the other way). But, then you will void the warranty. Please don't ask which wire is +/-, cause I don't know when it comes to that fan (there's 4 wires). Anyway - this might be a bad idea if you don't know exactly what you're doing.


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## Hunteil (Mar 30, 2007)

lol i'm not even going to bother.... i guess i'll buy a new one....the thing is that the fan i bought and have currently i look online and the fins show it blowing down.... http://www.geeks.com/details.asp?invtid=C91968-001&cat=FAN
weird.... :-(


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## mattlock (Dec 28, 2005)

Are you certain that it's exhausting away from the heatsink? I have one Intel system with a similar fan, and if I out my hand by it it feels like it's exhausting air when it's intaking air(verfied with the paper trick). It intaking air at such a velocity that all air can't go through the heatsink, so some air is deflected off the heatsink making it seem like it's exhausting instead of intaking.


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## Hunteil (Mar 30, 2007)

whats the paper trick?


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## mattlock (Dec 28, 2005)

Hold a piece of paper larger than the fan in front of the fan and see if it's drawn towards it or blown away from it. That fan doesn't have very good guard on it so just be carefully. 
Cigarette smoke usually works pretty well, but I couldn't tell using that method due to the PSU fan and the nature of the heatsink fan.


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## pt121984 (Mar 21, 2007)

I have three of these fans and they all blow down on the CPU. I have one system that I have in an older P3 Inwin Case tha the cpu runs a little hot, but I'm going to cut a hole in the side panel and install a 120mm fan. When the side panel is off it runs about 8 degrees cooler, so doing this should drop my temps. The fan will pull from the outside down onto the cpu. 

Patrick


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## Hunteil (Mar 30, 2007)

Okay I'll rewrite this since this died on me last night.

I decided to take off the fan, which was easy... I cleaned it all off and reapplied the greese... I then released that the was the screwed tighten was opposite from what I read in the directions for attachment... the arrows on the faseners point the direction to actully loosen the cpu fan... The directions I read said opposite. O well. I also think I put too much greese on it since the base of the heatsink obly covers a circle size not a square. After reassembly which was easier said then done my computer is now working!

NOTE FOR THIS CPU FAN... When locking screws in place you have to press super hard to get it to go... Most the time it don't even pop like the directions say it does. Your best off pressing down with the screw driver and watchign with a flashlight and mirror on the side to ensure it touches the top of the inside. If you fail to do this, the thing will slide into place right it seems but pull pop/spring up or move quitely back to unlocked position. I 1st didn't press hard for fear of damaging the mother board. I still don't know if the noise I heard was it popng or my board.

I went to BIOS and the temp in processor was now at 56C... going to be high in BIOS. In Idle is was 40-50C....I reset my temp warnings to 68C and it'll warning me it's getting too hot... in load playing warcraft 3 I did not get any warnings which is saying that it never even reached 68C. Thanks all for the help. I hope this helps you all in the future.


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## mattlock (Dec 28, 2005)

Personally, I wouldn't set the temp alarm any higher than 60c.

BTW to much thermal compound is just as bad as not enough. Take a look at the link below for proper application instructions.

http://www.arcticsilver.com/arctic_silver_instructions.htm

Matt


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## Hunteil (Mar 30, 2007)

I'm using antic silver 5... I did use the directions.

Quote:
I went to BIOS and the temp in processor was now at 56C... going to be high in BIOS. In Idle is was 40-50C....I reset my temp warnings to 68C and it'll warning me it's getting too hot... in load playing warcraft 3 I did not get any warnings which is saying that it never even reached 68C. Thanks all for the help. I hope this helps you all in the future. 

Change: I reset my temp warnings to default on my system, if I would set my warning to 60C then the computer couldn't even play a game. I'm not too worried about it though.

my temp 2 location witch when i looked it up on my motherboard it was located between the processor and RAM insert location as the diagram showed.... We it's just a spot on the motherboard and now I get errors for that being too hot... current max warning is set for 50C playing WOW sets it off though... Looking at the spot I moved the RAM over awhile back to the far side to allow ample room for air flow there. I also notice there is no wires, no nothing getting in the way.... Any way or tips to keep this spot cooler?

Also motherboard temp level what is the standard for them?


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## mattlock (Dec 28, 2005)

95five-0 said:


> Also proper air flow should be suck in from the front and blow out the rear. If you have too many fans blowing different directions it could hurt your cooling.


[OUOTE=Tumbleweed]> 
Bottom line, heatsink fan blowing down, back fan pulling hot air OUT of case, front fan pulling cool air in......those are almost a necessity with this CPU. [/QUOTE]


Have you turned the rear fan around to make it exhaust as Tumble and 95Five0 suggested? They are both 100% correct on the fan configuration. You might consider adding more exhaust fans in the rear if your case has open fan slots.

Could you post your motherboard make and model and also your case. (A link to the case would be nice) I'd like to have a look at what we're dealing with.


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## Girderman (Oct 22, 2006)

I didn't read the whole thread, so may have missed something critical but I still want to say that your case fan set-up is wrong. First I think you probably have too many fans which is not so bad if your Power Supply can handle it. Have you done a Power Analysis on your system to find out if your Power is adequate.

But the main message is your case circulation is all wrong. I'm no expert but even I can see that. Air needs to move in one consistant direction which is usually front to back. I've never read of a back-to-front system that case cooling experts didn't have serious objections to.

I think the idea of reversing the CPU fan to be a bad idea. I once mounted a CPU fan upside-down on the heat sink by accident, and temperatures were at least 10 degrees higher until I figured out what I did wrong.

But, as an "experiment", you might try getting a file and filing away the excess "channel" plastic on the CPU fan's power wire, so that the "keyway" (that forces the plug to go only one way and not the other) is removed and the plug can be inserted either way.

This seems less drastic than chopping wires. If the experiment goes bad, you can just flip the plug back the way it is supposed to be.


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## Hunteil (Mar 30, 2007)

The CPU fan does blow into the CPU heatsink. So reversing it is pointless now. Thanks though.


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## Hunteil (Mar 30, 2007)

Intel D925XBC Socket 775 mATX MBB w/Gigabit LAN & Hi-Def Snd
http://www.geeks.com/details.asp?invtid=D925XBC-WB

10-Bay Matrix ATX Window Case w/450-Watt PS (Silver)
http://www.geeks.com/details.asp?invtid=SIL-CP702-2

A-Power 500-Watt 20+4 pin ATX Dual Fan Power Supply
http://www.geeks.com/details.asp?invtid=AP500W


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## mattlock (Dec 28, 2005)

Download Sensorview from the link in signature and post all the info it gives you. With your M/B temp going over 50c I have to wonder if that low quality PSU is possibly overvolting causing your temps to elevate. (You cannot get a good PSU for $20) You could also consider adding a fan to the NB heatsink.

Here's a fantastic PSU deal, but today the sale ends today. Antec Earthwatts 500w $40 after $30 rebate.


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