CPU fan blows air to cool or pulls off hot air coming off

Speed addicts anonymous.

Moderator: Starfalcon

CPU fan blows air to cool or pulls off hot air coming off

Postposted on Mon Jun 18, 2012 9:44 pm

sorry for the n00b question, but is the CPU fan pushing cooler air onto the hot heatsink to cool off the CPU or is it pulling the heat coming off heatsink to cool it down?

there are a few reasons I'm asking.

1) I removed the heatsink fan to clean out the sunk-in dust and was not quite sure what was the original orientation of the fan.
2) I was thinking of how people put a fan at the house window to pull air from the outside and blow it into the house.

Right now, I have an AMD Phenom II X4 940. for most things, it stays cool fine. but when I'm running a very long 100% CPU intensive task like video encoding, it starts to overheat. So right now, I'm having to aim a desk fan at the inside of my case. So now, my CPU temps will stay around 60C when at 100% CPU for 24+ hours.
Last edited by onlysublime on Mon Jun 18, 2012 11:15 pm, edited 1 time in total.
onlysublime
Gerbil
 
Posts: 81
Joined: Sat Jul 16, 2005 3:20 pm

Re: CPU fan blows air to cool or pulls off hot air coming of

Postposted on Mon Jun 18, 2012 9:49 pm

Fan on a heatsink usually is blowing down to cool the heatsink.

Your fan might have arrows on the side showing proper orientation or which side blows air.

Another way to figure out is the plastic bars supporting the fan motor face down not up.
Last edited by biffzinker on Mon Jun 18, 2012 9:52 pm, edited 1 time in total.
biffzinker
Gerbil First Class
 
Posts: 114
Joined: Tue Mar 21, 2006 3:53 pm
Location: Anchorage, Alaska

Re: CPU fan blows air to cool or pulls off hot air coming of

Postposted on Mon Jun 18, 2012 9:50 pm

Fans usually blow toward the label on the hub.
It is one of the blessings of old friends that you can afford to be stupid with them. Ralph Waldo Emerson.
Captain Ned
Global Moderator
Gold subscriber
 
 
Posts: 20208
Joined: Wed Jan 16, 2002 7:00 pm
Location: Vermont, USA

Re: CPU fan blows air to cool or pulls off hot air coming of

Postposted on Mon Jun 18, 2012 11:14 pm

thanks for the quick replies! very much appreciated.

I'll have to look at the fan again. the way I remember it, both sides of the fan has a label so I'm not sure which label is supposed to face the heatsink.

so when I look for an arrow, the arrow is supposed to point toward the heatsink?
onlysublime
Gerbil
 
Posts: 81
Joined: Sat Jul 16, 2005 3:20 pm

Re: CPU fan blows air to cool or pulls off hot air coming of

Postposted on Mon Jun 18, 2012 11:48 pm

Yes it should point towards the heat-sink (The direction the air pushes towards). If its not... then please share with us what brand heat-sink you have, or is it an OEM HSF?
"I think there is a world market for maybe five computers."
Thomas Watson, chairman of IBM, 1943

i5-2500K|Asus P67 Sabertooth|16GB Corsair 1600|MSI 7850 2GB|250gb Evo 840|Corsair 400R|ET750w PSU|Logitech G5|Dell 2420L|Corsair Vengeance 1300
Welch
Minister of Gerbil Affairs
Gold subscriber
 
 
Posts: 2639
Joined: Thu Nov 04, 2004 5:45 pm
Location: Fairbanks, Alaska

Re: CPU fan blows air to cool or pulls off hot air coming of

Postposted on Tue Jun 19, 2012 5:59 pm

It is a standard heat sink fan that came with my AMD Phenom II x4 940.
onlysublime
Gerbil
 
Posts: 81
Joined: Sat Jul 16, 2005 3:20 pm

Re: CPU fan blows air to cool or pulls off hot air coming of

Postposted on Tue Jun 19, 2012 7:44 pm

Yea it should be blowing air onto the heatsink between the fan and the CPU.

If adding an outside fan helps that much, there are a couple things you can do to likely help reduce your CPU temps. First, see if you can do anything to clean up the cables and things inside the case. First, make sure everything inside the case is clean of dust. Especially fans and heat sinks. Take anything that's dangling in the middle of the case and use zip ties to help move it out of the way. This can help a suprising amount. If you can increase the speed of any case fans, or possibly add a case fan, that can be a very inexpensive way to help as well.

If you do this a lot and can spend a little money, I'd recommend an aftermarket fan/heatsink combo. Noctua for example has some great designs, and if any of them are compatible with your system they stand a good chance to cool your CPU a lot better.
MJZ82
Gerbil
 
Posts: 63
Joined: Tue Nov 24, 2009 2:24 pm

Re: CPU fan blows air to cool or pulls off hot air coming of

Postposted on Tue Jun 19, 2012 8:34 pm

onlysublime wrote:sorry for the n00b question, but is the CPU fan pushing cooler air onto the hot heatsink to cool off the CPU or is it pulling the heat coming off heatsink to cool it down?
The way to answer that question is to ask yourself: when you are overheating, your sweaty skin are the fins of your heatsink, and which way do you want a fan pointed then? :P
UberGerbil
Gerbil Khan
 
Posts: 9976
Joined: Thu Jun 19, 2003 3:11 pm

Re: CPU fan blows air to cool or pulls off hot air coming of

Postposted on Wed Jun 20, 2012 11:13 am

Push/Pull doesn't make that much difference really, though push is slightly better for cooling and pull is slightly quieter.

Without getting all Thermodymanics nerd, stirring the air that passes through a heatsink increases the average temperature delta between the fins and the fluid, so more heat leaves the fins goes into the fluid.
Fans stir air, so your heatsink works better if you feed it stirred air, than if you suck unstirred air through it.
stirred fluid makes more noise; think of river rapids compared to calmer moving water (totally inaccurate/wrong analogy, but since the air/fin turbulence interactions give a similar noise increase, it kind of works).

The noise reduction from pull-instead-of-push configurations is minor though, since the main culprit is the fan blade itself, not the interaction between the air and the heatsink.
<insert large, flashing, epileptic-fit-inducing signature (based on the latest internet-meme) here>
Chrispy_
Gerbil Jedi
Gold subscriber
 
 
Posts: 1841
Joined: Fri Apr 09, 2004 3:49 pm

Re: CPU fan blows air to cool or pulls off hot air coming of

Postposted on Wed Jun 20, 2012 12:55 pm

MJZ82 wrote:Yea it should be blowing air onto the heatsink between the fan and the CPU.

If you do this a lot and can spend a little money, I'd recommend an aftermarket fan/heatsink combo. Noctua for example has some great designs, and if any of them are compatible with your system they stand a good chance to cool your CPU a lot better.


alright, first off, I'd like to thank everyone for really helping me out! I learned a lot from you guys.

and second, I looked up the Noctua fan/heatsinks on Amazon and saw this (NH-U12P SE2 CPU Heat Sink With 2 Noctua Fans) for $65, and went ahead and bought it. Hopefully this solves 2 problems which is the loud fan I currently have on the CPU and the overheating problem.

The last question I have is this: I've never owned such a large heatsink before. This is a monster in my eyes. I do move my PC around a lot (LAN gaming, hooking the PC to a TV in the other room for recording, etc.). Any tips for moving it with such a monstrous heatsink on it? or is it a concern I shouldn't have to worry much about?

here's the Noctua I got. any comments would be much appreciated as well. If there are better options for the price, I'll return it.

Image

http://www.amazon.com/gp/product/B002N2JVEE/ref=ox_sc_act_title_1?ie=UTF8&m=A1BVYXEL822RF0

I came in expecting to get some insightful answers and walked out buying a new heatsink which I didn't anticipate. :)
onlysublime
Gerbil
 
Posts: 81
Joined: Sat Jul 16, 2005 3:20 pm

Re: CPU fan blows air to cool or pulls off hot air coming of

Postposted on Wed Jun 20, 2012 1:16 pm

You shouldn't have to much of a concern with moving it. Just make sure that you don't have cables resting on top of it or pushing against it. There will be 4 screws in the back of the motherboard with a support plate, as long as those are secured properly it would take an act of god (or one hell of an act of clumsiness) in order to knock it off.

Make sure too that your case has clearance (deep enough) for the tall Heatsink. I'm not sure what sort of paste that one comes with, but if it doesn't have any on it, I'd recommend Arctic Silver 5. Since you'll have a HSF that's capable of moving more heat, you'll want a paste that can keep up with it. You may have to take your motherboard out to install that heatsink IF your case does not have a cut out on the backside to allow you to install it while its in the case, just keep that in mind.

Otherwise, I think your going to love it :). Best of luck.
"I think there is a world market for maybe five computers."
Thomas Watson, chairman of IBM, 1943

i5-2500K|Asus P67 Sabertooth|16GB Corsair 1600|MSI 7850 2GB|250gb Evo 840|Corsair 400R|ET750w PSU|Logitech G5|Dell 2420L|Corsair Vengeance 1300
Welch
Minister of Gerbil Affairs
Gold subscriber
 
 
Posts: 2639
Joined: Thu Nov 04, 2004 5:45 pm
Location: Fairbanks, Alaska

Re: CPU fan blows air to cool or pulls off hot air coming of

Postposted on Wed Jun 20, 2012 8:10 pm

That's my heatsink!
Noctua are awesome - they're not the cheapest, nor the most efficient but they ARE quiet and when you upgrade to a new motherboard socket in the future, they'll give you the new mounting hardware for free.

My advice would be to lay the PC down so that the heatsink is vertical if you're driving it anywhere by car. It's probably not necessary, but you don't want to have to find out the hard way.
<insert large, flashing, epileptic-fit-inducing signature (based on the latest internet-meme) here>
Chrispy_
Gerbil Jedi
Gold subscriber
 
 
Posts: 1841
Joined: Fri Apr 09, 2004 3:49 pm

Re: CPU fan blows air to cool or pulls off hot air coming of

Postposted on Wed Jun 20, 2012 8:23 pm

Chrispy_ wrote:That's my heatsink!
Noctua are awesome - they're not the cheapest, nor the most efficient but they ARE quiet and when you upgrade to a new motherboard socket in the future, they'll give you the new mounting hardware for free.

My advice would be to lay the PC down so that the heatsink is vertical if you're driving it anywhere by car. It's probably not necessary, but you don't want to have to find out the hard way.


I ALWAYS lay mine down when I travel. And the fan I have on my little server, I have the fan pulling the air through the heatsink. I cant remember now why I decided to do it this way.
But the norm is the fan blows through the heatsink.
i7-2600k (4.1Ghz), 16GB DDR3-1600, 6970 2GB, GA-Z68X-UD3H-B3, Recon3D Audio (PCI-E), WD 1TB Black (os/programs), WD 2TB Green (games), WD 3TB Green (movies/music), Win 8.1 Pro x64
Check out my site for trance mixes and other goodies! linserv.biz.tm
ClickClick5
Gerbil XP
Gold subscriber
 
 
Posts: 452
Joined: Fri Aug 15, 2008 8:28 pm
Location: Somewhere in a land the doctor says does not exist...

Re: CPU fan blows air to cool or pulls off hot air coming of

Postposted on Thu Jun 21, 2012 4:56 pm

Well you definetly got the cream of the crop as far as quiet coolers are concerned. You shouldn't have any trouble with that Noctua. In case you're interested, here's a quick temperature and noise comparison to some other heatsinks on the market. As you can see, stock coolers are never as quiet or effective as a tower-style cooler.
i5-3570K, ASRock Z77 Pro4-m, Asus GTX660 TOP, 120 GB Vertex 3 Max IOPS, 2 TB Samsung EcoGreen F4, 8GB G-Skill @1.25V, Silverstone PS07B
DPete27
Gerbil Jedi
Silver subscriber
 
 
Posts: 1634
Joined: Wed Jan 26, 2011 12:50 pm
Location: Madison, Wisconsin

Re: CPU fan blows air to cool or pulls off hot air coming of

Postposted on Wed Jun 27, 2012 5:08 pm

alright finally got this beast of a HSF (to me, who has never experienced anything other than a stock HSF) in the mail.

and at the website's FAQ, they show 2 orientations. Is one preferable to another:

Image
onlysublime
Gerbil
 
Posts: 81
Joined: Sat Jul 16, 2005 3:20 pm

Re: CPU fan blows air to cool or pulls off hot air coming of

Postposted on Wed Jun 27, 2012 5:16 pm

The idea is: Hot air in your case = bad, Cold air in your case = good. If you can get the fans to blow air towards an exhaust point (rear fan) in a short distance, you will get heat out of your case faster. If the heat lingers in your case, you will be "cooling" your heatsink with warm air, thus allowing the equilibrium temperature to reach greater heights (Your CPU may overheat). Option 1 is ideal, but it really depends on the orientation of your particular case/components. You want air to exit the case with little resistance to airflow (wires/junk/space in the way).
BloodSoul
Gerbil First Class
 
Posts: 135
Joined: Tue Apr 06, 2010 1:49 pm

Re: CPU fan blows air to cool or pulls off hot air coming of

Postposted on Wed Jun 27, 2012 8:40 pm

thanks for the tips!

after putting everything into the case, I can see how option 1 is definitely better. but it's a moot point with my AMD setup since to get option 1, I would need to get an optional accessory for it to be oriented that way. I already spent $65 on this which is $65 more than I expected.

with option 2, there's not much clearance between my PCI express Hauppauge tuner card and the HSF. the picture above is overly optimistic and doesn't show any cards at all whereas my system has a video card that takes up 2 slots (heightwise due to an oversized fan system), the Hauppauge tuner card that is between my video card and the HSF, and another Hauppauge tuner card below the video card.

but man, the Noctua package is quality! the packaging is probably the most professional packaging I've ever seen in a tech product. The Chinese companies should take some cues from the Austrians! It rivals what you would see with an Apple or Microsoft product. It comes with everything! well, except that option accessory which I really want!
onlysublime
Gerbil
 
Posts: 81
Joined: Sat Jul 16, 2005 3:20 pm

Re: CPU fan blows air to cool or pulls off hot air coming of

Postposted on Thu Jun 28, 2012 5:42 am

What could that optional part really be? A plastic retainer to make it stay on the other side of the HeatSink?

I'd really suggest getting it if it means you can use orientation option "1"... but first, here are a few questions.

1. What case are you using?
2. Do you have a Power supply on bottom or top
3. Do you have fans out the top of your case?

I realize questions 2 and 3 could be answered if you told me one... but I couldn't just ask 1 question after numbering them! Anyhow. If you have a PSU at the top like their picture, then you DON'T want option 2. However, if your PSU is on the bottom (which is typical these days) and you do have either a place to mount a fans, or you do have fans blowing up and out the case, then Option 2 would be ideal. Which is it?
"I think there is a world market for maybe five computers."
Thomas Watson, chairman of IBM, 1943

i5-2500K|Asus P67 Sabertooth|16GB Corsair 1600|MSI 7850 2GB|250gb Evo 840|Corsair 400R|ET750w PSU|Logitech G5|Dell 2420L|Corsair Vengeance 1300
Welch
Minister of Gerbil Affairs
Gold subscriber
 
 
Posts: 2639
Joined: Thu Nov 04, 2004 5:45 pm
Location: Fairbanks, Alaska

Re: CPU fan blows air to cool or pulls off hot air coming of

Postposted on Thu Jun 28, 2012 6:09 am

I must be wrong again as I looked for the text I read before and can't find it.

here's what the FAQ for my HSF says:

Can the cooler be installed turned by 90° on AMD sockets?
No. The new SecuFirm2™ mounting system for AM2, AM2+ and AM3 uses the same standardised hole
spacing as the Intel system and thus allows for a much easier installation, but the cooler cannot be installed
turned by 90°.

So it appears I'm stuck moving air upwards through the power supply.

As for my case, I'm using a Coolermaster Centurion 5. The power supply is on top. There are no fan outlets on top of the case.

Image

I actually had to remove the funnel on the door because the new HSF was too big.

Image

Oh, these pics are from google and are not of my system.

alright, one more question (hopefully!!!!): now previously with the old HSF, I had to have my case open and pointed a desk fan at the inside to keep it cool. and under a full CPU load, it ran around 60-62C (with an open case and a desk fan pointed at the insides).

with the new Noctua HSF, under a full CPU load with the case open, it runs around 52C (no desk fan needed! woohoo!). but I close up the case and the temperature rises to around 62C. So I definitely need at least a case fan out the back of the case. so any good places to buy one and any good types (I'm really bad with cooling apparently)?

And I'm loving the silence of this HSF!!!! On the stock HSF, when my CPU went to 100%, my fan on the heatsink whirled up to really loud levels (actually very distracting and actually much louder than my desk fan) and it was still not cooling my CPU well.
onlysublime
Gerbil
 
Posts: 81
Joined: Sat Jul 16, 2005 3:20 pm

Re: CPU fan blows air to cool or pulls off hot air coming of

Postposted on Thu Jun 28, 2012 9:31 am

I had/have the same case. Long story short, that 80mm fan in the front of the case does not provide enough air flow into the case. This means that it's a "negative pressure" case where there is more air leaving the case than entering.
Heres what I did: Grab a quiet 80mm fan (here's the one I got). Get a side cutter and clip out a hole in the middle of the lower grillage on the side panel (approx. above the GPU). You'll want to cut the grillage out instead of just installing the fan behind it because the grillage is too close to the fan blades and does not allow enough air flow so your fan will sound louder because it's working harder to suck air through it. File down sharp edges and use a black sharpy marker to hide the unpainted metal edges where you've cut.
If you choose the correct holes, you can install the 80mm fan with a spare fan grill using the standard fan screws. Doing this feeds cool air into the case directly at the CPU / GPU area which helps the weak 80mm front fan that only really cools the hdd cage. I had an Intel setup so my tower style heatsink (like your new one) was able to blow toward the rear 120mm case fan, so I didn't see much difference in CPU temps. But this mod did make my GPU run 10C cooler while spinning at lower rpms than before.

If you can fit a 92mm fan in there it would be quieter and move more air than an 80mm one. I don't have any 92mm fans to see if that would work, but there are fan templates you can use to check.
i5-3570K, ASRock Z77 Pro4-m, Asus GTX660 TOP, 120 GB Vertex 3 Max IOPS, 2 TB Samsung EcoGreen F4, 8GB G-Skill @1.25V, Silverstone PS07B
DPete27
Gerbil Jedi
Silver subscriber
 
 
Posts: 1634
Joined: Wed Jan 26, 2011 12:50 pm
Location: Madison, Wisconsin

Re: CPU fan blows air to cool or pulls off hot air coming of

Postposted on Thu Jun 28, 2012 10:29 am

wow! that's some great insight.

I'm a little unclear about what you're describing. The side panel has 2 grillage areas. The top grillage area is shaped like a hexagon and is right at the same level as the Noctua HSF. There's probably less than an inch of space between the HSF and the panel. The bottom grillage area for the side panel is shaped like a rectangle and is below the HSF but the area is about the same level as the GPU.

So what you're saying is to cut through the grills of the lower area enough so that I wedge in the 80 mm fan? So this fan will not be flush with the panel (will stick out a bit)?

So this case will be having 3 fans:
120 mm case fan at the rear to pull air from the case to go to the outside
80 mm fan in the front of the case to pull air into the case
80 mm fan on the side panel to pull air into the case

alright, I have a mea culpa... a few months ago, my rear case fan started making some horrific sounds so I disconnected that fan. so I'm going to have to get one of those. I don't remember about the front fan so I'll have to get one of those as well. So I guess I'm in the market for 3 case fans...
onlysublime
Gerbil
 
Posts: 81
Joined: Sat Jul 16, 2005 3:20 pm

Re: CPU fan blows air to cool or pulls off hot air coming of

Postposted on Thu Jun 28, 2012 10:41 am

Suggest replacing the rear case fan first, and then testing the system, before going wild with additional mods. That may be all the help you really need because you probably have a "hot pocket" forming around the GPU, CPU, and motherboard voltage regulators due to inadequate airflow.

Since you're not using the CPU funnel vent, you might want to block that upper vent so that the rear case fan is forced to pull air from the lower vent, which will help maintain airflow around the GPU area.
He who laughs last, laughs first next time.
ludi
Gerbil Elder
 
Posts: 5429
Joined: Fri Jun 21, 2002 10:47 pm
Location: Sunny Colorado front range

Re: CPU fan blows air to cool or pulls off hot air coming of

Postposted on Thu Jun 28, 2012 11:35 am

onlysublime wrote:So what you're saying is to cut through the grills of the lower area enough so that I wedge in the 80 mm fan? So this fan will not be flush with the panel (will stick out a bit)?


Yes the lower square shaped grillage, not the one directly above the CPU. My 80mm fan was mounted inside the panel and cleared my 6850 just fine.

onlysublime wrote:alright, I have a mea culpa... a few months ago, my rear case fan started making some horrific sounds so I disconnected that fan. so I'm going to have to get one of those. I don't remember about the front fan so I'll have to get one of those as well. So I guess I'm in the market for 3 case fans...


Then I definetly agree with Ludi. You absolutely need that 120mm exhaust running to get the hot air out of your case. In fact this may have been your problem all along. A 120mm fan will cost about $12 and $8ish for an 80mm. Thats $20 for two case fans. This case only costs $50 (or less). You might be better off spending that $20 toward a new case that fits your AM3 orientation better.
i5-3570K, ASRock Z77 Pro4-m, Asus GTX660 TOP, 120 GB Vertex 3 Max IOPS, 2 TB Samsung EcoGreen F4, 8GB G-Skill @1.25V, Silverstone PS07B
DPete27
Gerbil Jedi
Silver subscriber
 
 
Posts: 1634
Joined: Wed Jan 26, 2011 12:50 pm
Location: Madison, Wisconsin


Return to Overclocking, Tweaking, & Cooling

Who is online

Users browsing this forum: No registered users and 1 guest