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Need help in case fan arrangement

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June 4, 2010 12:10:47 PM

A month or so ago, I completely took out my PC parts to give them some cleaning. Expecting a drop in temps of a few degrees, I was shocked to find out that my CPU temps rose from 40-43 to 49-51 degrees Celsius. I initially thought it was the thermal paste that was faulty, since I replaced it with generic thermal paste (it initially had whatever Intel placed along with their stock HSF). I then replaced it with another less generic thermal paste that allegedly had silver. Temps dropped to 47-49 degrees, which was still far from my 40-43 temps before.

More recently, I modded my case by adding a second fan in front, seeing as the initial fan seemed rather bleak. I also added a side fan on the free slot directly facing the CPU and HSF. Weirdly though, my CPU temps remained the same. I identified the problem, it was that the new side fan was serving as exhaust, which contradicted the HSF which was sucking air in. I replaced it and the temps dropped to 46-48 degrees.

Right now, my case is a simple generic case. My fan set-up is as follows: 2 120mm front fans sucking air into the case, two side fans, one 120mm directed to the GPU, one 80mm fan directed at the CPU, both sucking in air as well, and lastly, a rear 80mm fan acting as exhaust. If it matters, my PSU is located at the top, with the its 150mm fan sucking air in, to be expelled through the back.

My worry is that I have too much intake and too little exhaust. Do you guys think that I should make adjustments? I'd like to reduce my CPU temps without having to spend for a new cooler.

Oh, and additional info, I live in a tropical country, and I have an undervolted and overclocked E6550 running at 2.80 GHz and 1.040V.

Sorry for the lengthy post and thanks for your input :) 

More about : case fan arrangement

a b ) Power supply
June 4, 2010 1:36:27 PM

Hi.

Check the correct installation of the HSF and adjust the fans to 2 intake and 3 exhaust.
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a b ) Power supply
June 4, 2010 5:14:34 PM

To OP:
Agree with more exhaust might work for you. Reverse the fans at the side to become both exhaust.
Most probable cause of the hotter CPU is because the fan at the GPU side is taking in air and blows to the hot GPU. This hot air will flow up right into your CPU.
By making it exhaust, the cool air will come from the front, pass thru the hot GPU and be sucked out of the 120mm fan on the side before it rise to the CPU area.
As I mentioned, you have to make the 80mm at the front of the CPU exhaust too because if you make it intake, it will just suck back the hot air pulled out from the GPU and blow it right back to the CPU.

Hope this helps.

By the way, what is your PSU's model? Does it have the fan at the bottom or at the rear? If the PSU is at the top but it's air intake is at the bottom, there will be trapped hot air at the top of the case. Not that it is causing your higher temp because you said it was running cooler before unless there was a change in this department too.


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June 5, 2010 5:44:39 AM

randomkid said:
To OP:
Agree with more exhaust might work for you. Reverse the fans at the side to become both exhaust.
Most probable cause of the hotter CPU is because the fan at the GPU side is taking in air and blows to the hot GPU. This hot air will flow up right into your CPU.
By making it exhaust, the cool air will come from the front, pass thru the hot GPU and be sucked out of the 120mm fan on the side before it rise to the CPU area.
As I mentioned, you have to make the 80mm at the front of the CPU exhaust too because if you make it intake, it will just suck back the hot air pulled out from the GPU and blow it right back to the CPU.

Hope this helps.

By the way, what is your PSU's model? Does it have the fan at the bottom or at the rear? If the PSU is at the top but it's air intake is at the bottom, there will be trapped hot air at the top of the case. Not that it is causing your higher temp because you said it was running cooler before unless there was a change in this department too.


Thanks for the input. I'll try reversing the two side fans to check for any improvement.

My PSU is a HEC Cougar 550W PSU, which I recently bought to replace my Corsair CX400. This shouldn't be an issue though, because both of them were located at the top with the fans at the bottom.
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June 5, 2010 8:04:55 AM

Guys I tried your suggestion, but sadly, it increased both my CPU and GPU temps by 2 degrees. Subsequently, I returned the side fans to their previous intake orientation.

Does that mean this is the most optimal my fan set-up can get?
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a c 104 ) Power supply
June 5, 2010 9:49:56 AM

Just my humble,

for now you could swap one of the 120's from the front and have that at the rear as an exhaust instead of the 80mm that you currently have,

look into getting a pci slotfan to sit under your gfx card maybe as well.

My current set up is more intake than exhaust, but its dependant on cable management and where the Rig lives,

each pc is different and what works for me may not be the best set up for you, but try the adjustment above and see how you go, I'll check back ofc,
Moto
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June 5, 2010 3:33:46 PM

I had long thought of doing that, but sadly, my cheapo case has space for an 80mm fan only at the rear. :( 
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a c 104 ) Power supply
June 5, 2010 8:16:44 PM

hmm, how about 4x80mm's in the roof as exhausts?
Moto
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a b ) Power supply
June 5, 2010 11:59:01 PM

Is the ambient temperature in your room higher now than when you had the low temperatures? Are you testing under the same operating conditions? This could affect your temperatures.

As for the thermal paste: I would suggest artic silver 5 (or the equivilent.) Please do keep in mind that this paste and a few others have a certain "burn in" time. Perhaps this is why your cpu is running a few degrees hotter with a fresh paste install.

If you're still worried about temperatures you could always just get some better fans to push more air through your case. If you're going to spend the money doing that you might as well just get a better case instead. I've seen quite a few nice cases with great airflow for sub $100.
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June 6, 2010 7:12:33 AM

Motopsychojdn said:
hmm, how about 4x80mm's in the roof as exhausts?
Moto


I've already stated that I've filled up all the fan slots of my case. And 4 80mms in the roof?! That would mean replacing the whole top part of my case with a screen or something. Or was this a sarcastic suggestion?

ssddx said:
Is the ambient temperature in your room higher now than when you had the low temperatures? Are you testing under the same operating conditions? This could affect your temperatures.

As for the thermal paste: I would suggest artic silver 5 (or the equivilent.) Please do keep in mind that this paste and a few others have a certain "burn in" time. Perhaps this is why your cpu is running a few degrees hotter with a fresh paste install.

If you're still worried about temperatures you could always just get some better fans to push more air through your case. If you're going to spend the money doing that you might as well just get a better case instead. I've seen quite a few nice cases with great airflow for sub $100.


My old temps were measured last year, around August, right in the peak of our rainy season. I would say it's a bit colder than it is now, since summer's just ending and the rainy season's just kicking in. However, I don't think that could cause a change of 5 degrees, for the ambient temps don't change by 5 degrees either.

Fans here cost about $1.20 for 80mm fans and $1.60 for 120mm fans. Sadly, more fans isn't possible because I don't have space for it anymore inside the case. Most of the cases here sell for about $30, with very few people actually buying Antec 300s or whatever in that price range which you guys consider as "affordable".
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a c 104 ) Power supply
June 6, 2010 7:54:37 AM

Yup, Adding 4x80mm's would mean some proper modding of your case I'm afraid,
I'm sorry if my earlier post was misconstrued as possible sarcasm, it wasn't.
I was offering you real cooling advice from my experiences

I have actually done 4x80mm's in my own build so I'm not just seeing if I can get you to hack up your case.

four fans inside the roof,

My little 80's cost me about £11 for 9 fans and 3 hdd coolers, random bargain off egay,



If you can imagine it, you can find a way to do it :) 
Moto
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June 6, 2010 8:19:15 AM

Woah. Now that I've seen the pictures, everything falls into proper perspective now. Thanks Moto, and sorry for misinterpreting your previous post as sarcasm. How were you able to open up space on top of your case?

BTW, very clean set-up, I see no stray wires at all. How were you able to achieve this?
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a c 104 ) Power supply
June 6, 2010 9:14:55 AM

Probably best thing is to give you the link to my build log,

http://www.tomshardware.co.uk/forum/forum2.php?config=t...
Its the life of my rig so far, I am very much a budget builder myself and I've modded just about everything I've ever owned to some degree, One thing i should mention, my Roof fans are intakes, yours imo should be exhausts.
Theres pics and walkthrough of the fans in the roof, any questions just post and Ill reply :) 
The cable management as youll see comes from another guys thread making me jealous I have redone it about 5 times just to get it looking good (imo ofc)
Moto
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