Which direction for fan on SK6?

[geek167]

Do I want it blowing on the heat sink or sucking the air?

 

[rachaelsdad]

You want it blowing down.

 

[moocat]

I second blowing down. And keep a can of air blast handy...gotta keep those closely spaced fins free of dust. Doesn't take long to tack 2-4C to your temp if it starts getting clogged.

 

[geek167]

doh. no wonder it is at 49c under a full load on an athlon xp 1800. When I switch back to the Athlon XP 1600 I'll fix it.

Thx

 

[moocat]

Is 49C high for a full load temp?! Just how much cooler clock for clock do the XPs run compared to regular Tbirds?

 

[helloedchen]

<< You want it blowing down. >>

 

[WA261]

amazing yall say this....i would love to see any info backing it up.....when i put on my 80mm i did the switch....went from sucking to blowing...GUESS WHAT?????? it went UP 2c!!!!!!! .....imho blowing in NOT the correct way......i have tested it...have yall????

right now, with it sucking, i am at 38c....tunes playing...cs loading servers....seti....and kaza on....also on the net.....

i dont get this trip with people saying you need to blow on it....sh*t people think about it.....heat travels out through the fins....when you blow you are screwing up this heat trans....why would you want to force the heat back down to the base????!!!!

 

[Howard]

How the hell does blowing down make heat stay in one place?

Heat will always travel from a warmer place to a cooler place, regardless of any outside forces.

Another thing - sucking with a fan on a heatsink without a shroud is very inefficient. If there's no shroud, then the fan could just take air outside the heatsink right below the fan. I'll try to illustrate.


airflow
^^^^^^^
----------------
= = = fan==
----------------
\\\\\\\\\\\\\\\\\\\\\\\\\<<<<<<<< air comes in here, only cooling the top of the fins/pins
heatsink\\\\\\\\\\\
\\\\\\\\\\\\\\\\\\\\\\\\\
\\\\\\\\\\\\\\\\\\\\\\\\\
\\\\\\\\\\\\base\\\\\\\\ - help it's god damned hot down here, i'm gonna melt!
_________
....cpu......

BTW, even if your logic was right, nobody could get past the crappy punctuation/spelling/grammar, excessive 'yalls' and also excessive periods.

 

[WA261]

it isnt making it stay in one place...but when you force it back the same path it came...wtf do you think, you are helping natural heat dissipation? fins are for the heat to travle out through, from the base....so, your saying that you let the heat travel out, or to the top of the fin....then you force it back down, and this is going to cool better??? you sound like a true idiot =)

look at your picture fu*ktard....your saying air only comes into play at the TOP of sink??? hmmmmm...guess that means no air is drawn THROUGH the sink...COOLING it.....?????



<< BTW, even if your logic was right, nobody could get past the crappy punctuation/spelling/grammar, excessive 'yalls' and also excessive periods. >>




so you have a stupid ass point, and now your grasping.......im not at work....do you really think i give a f*ck about how i type here???? :rollseyes:

 

[CStroman]

I have tried both blowing and sucking on my sk-6 and blowing was better.

 

the air blowing down into the heatsink is cooler then the air thats already there (fan replaces hot air with cooler air)
having the fan suck is the same thing in a sense, its replacing the hot air with cooler air

the cooler the air, the more heat it will pull from the heatsink, in turn cooling down the processor
the base of the heatsink will always be hotter then the air between the fins -- so the theory of "keeping yalls hot air down" is wrong

your results may vary, depending on tha air movement and temperatures of your case - remember, not everyones using the exact same shat

<< fu*ktard >>

 

[NesuD]

<< amazing yall say this....i would love to see any info backing it up.....when i put on my 80mm i did the switch....went from sucking to blowing...GUESS WHAT?????? it went UP 2c!!!!!!! .....imho blowing in NOT the correct way......i have tested it...have yall???? >>

Yea Bubba actually i have and you are dead wrong. With my delta 38 sucking my temps rose 5c from 41c to 46c. Socket A cpu temp diode dynamics are not as simple as is the fan sucking or blowing. Socket A temp diodes are normally skewed by a variety of variables which render them highly unreliable for precise temp reporting. It is a well known fact that the SK6 was designed to have a lot of air pressure exerted on its top as in a fan blowing down. It is necessary because of the thinfin design with it's closely spaced fins.

 

[moocat]

WA261, how do you manage to conjure up that much hostility in a discussion about fans and heatsinks?

 

[geek167]

I'll try both and see what I come up with. I think my main problem is that i have no thermal grease applied. I'll fix that when I switch to a green cpu sometime today or this week.

 

[WA261]

<< . It is a well known fact that the SK6 was designed to have a lot of air pressure exerted on its top as in a fan blowing down. It is necessary because of the thinfin design with it's closely spaced fins. >>



Can you show me a link to this information, from the site where it was designed?




<< With my delta 38 sucking my temps rose 5c from 41c to 46c. >>



Then keep it blowing =)

In my case when I was pushing air on the sink temps went up 2c.... I am sure others will get a diff results..depends on more then just hsf air flow i would think ..but if you don?t have an sk-6 and you have not tested it....I don?t need to here what you "think" you know.

Why it pissed me off is because peeps have heard that you need to blow on an sk-6...most don?t have one and haven?t tested it, but that doesn?t matter, because they heard it has to blow...so rather then say "test it both ways.. I don?t have one and haven?t tested it" they will just tell a person what they have heard is correct.....I told what I KNOW to be true for my sk-6.... =)

 

[dejacky]

I have an SK6 with the 38cfm Delta fan. I've tried sucking & blowing, & blowing lowered my temps by about 3 degrees celsius. After this improvement, I lapped my heatsink & used Artic Silver 3, which brought my temperatures down 5 degrees celsius. I'm going to Re-Lap my heatsink since I think I can make it flatter.

 

[Howard]

<< look at your picture fu*ktard....your saying air only comes into play at the TOP of sink??? hmmmmm...guess that means no air is drawn THROUGH the sink...COOLING it.....????? >>


That's exactly right. All fluids tend to move through the path with least resistance. Electricity also follows this.


<< it isnt making it stay in one place...but when you force it back the same path it came...wtf do you think, you are helping natural heat dissipation? fins are for the heat to travle out through, from the base....so, your saying that you let the heat travel out, or to the top of the fin....then you force it back down, and this is going to cool better??? you sound like a true idiot =) >>


Again I reiterate: a hotter substance will always share its heat with a cooler one. The ONLY way heat would be 'pushed back', as you say, would be to have the air HOTTER than the heatsink! How f*cking possible do you think that is? 100% efficiency is impossible, and sometimes it's a curse, too.

 

[WA261]

:rolls eyes:

trust me....when i have an 80mm fan sucking on the sink....air is going to travel through the bottom of the fins...


like i said....IN MY CASE temps went up with air blowing.....

 

[ScottyB]

Wait I am confused, isn't sucking air into a heat sink and blowing air into a heat sink the same thing? I might sound stupid but to me it sound like to terms for the same thing. Or did you guys mean blowing away from the heat sink and sucking into it?

 

[MemnochtheDevil]

I guess it could depend on the ventilation in your case, but my problem with having the fan sucking (pulling air up from the heatsink) rather than blowing (pushing air down) is that I would think by sucking more air would come from the area closer to the fan not at the bottom (where the heatsink is the hottest). I'd think that in most systems blowing down would be best.

Another thing to think about is that if air flow is equal in either direction by blowing air down the heat transfer from the heatsink to the air is optimal. Heat is flowing up and out the fins and having the air hit the coolest part of the fin first and the hottest last is optimal. If you've ever studied dialysis filters you'll know the term for the system I'm refering to, having opposite flows allows for the greatest transfer/reduction. My memory is failing me right know, might have to dig up a textbook. Doesn't necessarily apply here but the logic would seem to be the same.

Again, the way you case fans are set up can have a big effect on your setup, so try it both ways.

Mem

 

[BobSnob]

Blowing down from the top the air hits the flat bottom and sets up back pressure reducing the effectiveness of the fan. Sucking up results in only the ends of the fins getting cooled as the air moves in from the sides and then up (there is also a dead spot in the middle under the fan motor).

THE best direction for air flow is a side flow THRU the fins originating from a shallow oblique angle. The oblique angle ensures that the air hits the fins, exchanges heat, and moves thru to the other side. If this heated air is then carried directly to the outside of the case thru venting you have the best possible air-cooled system IMO. I haven't quite worked out how to make a permanent setup of this though.