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Fan Questions

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Last response: in Components
April 8, 2003 4:33:11 PM

Hello again,

I'm still building my case, and I have a few questions about fans.

a) I bought four coolermaster fans for my case. I was wondering in what direction they should be blowing...Right now, the fronts are all facing this what I want? Should the front two be sucking air, and the back two blowing air?

b) What db level for a fan would be pretty quiet? (with them and everything else running

c) Two of the four fans I bought have thermal sensors on them (five wires coming out of fan), two are connected with what I assume is the sensor. How should the sensor be placed? I was going to place these two fans at the front of my case.

d) All of the fans had small power connectors, and large ones in the box (the kind of power connector I'm used to seeing on HD's), do I need to use these?

e) Do the fans connect to the motherboard or the PSU?

f) Lastly...if I change the CPU Fan (upgrade it later on), should I re-apply thermal grease on the cap of CPU?

I'm new to this...thanks for any help you can offer.

More about : fan questions

April 8, 2003 5:28:07 PM

a. Yes it is best to have the two in the front blowing air in and the two at the back blowing air out.

b. Depends on how much rpm your fans are.

c. Somewhere out of the direct air bundle of the fans but in the area you want to cool with the fan. That way they measure the spot temperature inside your case and not the temperature of the air being blown in.

d. If the fans have low amperage (0.35 A and lower) they can be connected directly to the motherboard but you will need 4 free fan connectors on the motherboard to do that. Otherwise you use the 4-pin molex connector (the HD like connector) to connect them directly with the powersupply.

e. See d.

f. If you only replace the fan no... but if you also replace/remove the heatsink then you will need to re-apply the thermal grease.

My dual-PSU PC is so powerfull that the neighbourhood dims when I turn it on :eek: 
April 8, 2003 5:56:37 PM

Thanks a lot Svol, exactly what I needed...

I had a quick followup...which way on these case fans is the blow out side? Just wanted to double check. On the side of the fans there are two arrows, one pointing horizontally, the other vertically. I assumed that the horizontal arrow showed which way it rotated, and the vertical arrow showed which way it blew. Correct?
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April 8, 2003 7:51:16 PM

Correct. Put them so all the arrows that show the direction of the air point towards and out the rear of your case.

War Eagle<P ID="edit"><FONT SIZE=-1><EM>Edited by Auburn9698 on 04/08/03 02:52 PM.</EM></FONT></P>
April 9, 2003 3:50:56 AM

traditionally one has the front fans sucking in, rear fans blowing out.

You dont generally have the rear ones sucking in as they will just suck back in warm air put out by the Power supply.

Fan noise is very subjective. whats ok for one person isnt for another. and depends on the location of the case.
As mine is ontop my desk i cant stand fans that are louder than 32dBa.

You can place the fan sensors wherever you think appropriate. Not really needed for casefans IMHO, but for the fan on the heatsink its useful to have to better regulate CPU temp.

Fan power connectors either come in a small 3 pin connector, they plug into the motherboard, or a bigger 4 pin one. you can plug these straing into the power supply ones.
Most motherboards only come with 3 fan headers, so if you have lots of fans you will have to run them directly off the PSU. Besides, really high speed fans HAVE to be run that way. too much current draw from the motherboard.

yes, each time you take of the heatsink you should reapply thermal paste. if the heatsink has a thermal pad that needs to be scraped and cleaned off and thermal paste reapplied.
DO NOT re-use a heatsink that has a thermal pad.
Use thermal paste sparingly. half a grain of rice is more than sufficient to cover a AMD cpu core.

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