suck in or suck out on alpha pal-35t?

[han888]

anyone?

 

[Technonut]

It has always been my experience that the Alphas work the best with the fan(s) pulling out through the heatsink like Alpha designed them to work. The heat is drawn away from the heatsink, and exhausted out of the case either through the PS fan or rear case exhaust.

 

[Gogga]

I also agree that Alphas work better when sucking air out of the heatsink. It doesn't differ that much in temperature, but with a Thunderbird you dont want the hot air to blow over the motherboard if you set the fan to blow into the heatsink!

 

[ride525]

So, if I understand both these posts correctly, the heatsink performs best when the fan is set up to suck air in from the sides of the heatsink and exhaust the air out the top of the fan.

And it performs at a lower level when the fan blows from the top, down into the heatsink, exhausting out the heatsink sides.

Correct?

 

[? (=Þ)]

uh, real world test. I have a celeron 550, and i tried both sucking air off, and blowing air on. I find that i have 1-2 degrees C lower if i blow air onto the heatsink. This was tested on both a sunon and a ystech 60mm fan on a Alpha PAL6035.

 

[han888]

that's make me confuse! in my opinion may be blow in will more cooller than blow out, but i havent try yet, now i am in blow out! the heatsink will going hot if there is no air to blow it! just my opinion, about the suck out, how fast can the fans to sucks out the hot? i just felt with my delta 38cfm ( 72000 rpm) may be will more cooler the heatsink if i blow in

 

[Technonut]

I am just going by the way that Alpha designed and instructs that the fan be installed on their heatsinks. My T-Bird 800 idles in the low 30's Cel. and never has gotten past 40 Cel. at 1.85v under full load with the fan sucking out. I just think that Alpha has put enough time and research into their own product to know how it should be installed, and it works very well for me whether using a dual fan 7125, or the single fan 6035 that I am using now. If it works better for you the other way, by all means run it that way. I like the fact that the hot air is exhausted out of the heatsink, and is drawn right up and out of the bottom fan of my power supply, instead of blowing hot air against the heatsink and motherboard. I also think that the airflow is more efficient, not flowing against other fans.

EDIT: Another thing to think about is that the heat from the core travels from the bottom of the heatsink UP towards the pins/fins, not from the top down. It just makes sense to me at least, that heat rises, and would be best drawn off from the bottom up, not blowing it back down toward the source of the heat.

 

[CamaroGuy]

Sorry for getting on this thread kinda late, but...

straight from Alpha's website:


Which type of fan heat sink is better, "expulsion type" or "induction type"?

According to our tests, the induction type showed better results the the expulsion type. This is because we used an intake cover to draw air through the lower part of the heat sink for more heat dissipation from the lower part of the fins. However, if some other heat source is located near the heat sink, heated air would come into the heat sink and affect the thermal performance, so the choice must be made depending on the environment.


I know that they show the fan blowing out on their instruction sheet, but for them to post the above in the "Questions and Answers" section, they must have just made a mistake on the instructions.

Personally, I run the induction with 2 120cfm case fans.

-CamaroGuy

 

[Technonut]

Interesting...Some HSF's do perform better with the fan(s) blowing in. I have tried the FOP38 with the Delta fan both ways and found that it cools 3-4 degrees cooler blowing down on the HS instead of sucking out, but still does not cool as well as the Alpha. On both dual and single fan Alphas, I have found a 3-4 degree increase in cooling with the fans sucking out, not blowing in. I ran these tests with a Digital Doc3 which is supposed to be accurate to 1 degree, not the mobo probe. Again, it is a simple matter to reverse the fans and use whichever method works best for you.

 

[abracadabra1]

out
in never works as well

 

[CamaroGuy]

I kinda have to side with Alpha since their the ones who make the thing. They do say that the better results for induction can be attributed to the intake cover thing; do most people use it?

-CamaroGuy

 

[Ribbit]

I believe the reply from Alpha is a little contradictory. Not unusual considering it was probably written by someone whose English is a second language. I believe their illustration, which clearly shows air being drawn through the bottom of the heatsink and expelled through the top, is correct. If you look at their Q&A carefully they say they use the cover to "draw" air through the lower part of the fins. Just my opinon. I have mine sucking

 

[ride525]

Everyone,

Lets be clear here....

When you just say "sucking" ...that can mean two things....

1. sucking in from the sides and exhausting out the top
or
2. sucking in the top and exhausting out the sides...

Explain your flow direction please...

 

[Technonut]

Exhausting out of the top.

 

[Mikewarrior2]

Sucking would mean pulling air through the shroud on alpha's, reverse of most heatsinks, where air is BLOWN onto the fins.

Mike

 

[NOS]

Go with the alpha directions and have it suck out!

 

[ride525]

I just tried reversing fan on my Taisol HSF. (It works great by the way.)

The factory shipped way worked best......sucking in the top and blowing out the sides....about 2C cooler....

Oh, and the way that didn't work as well, sucking in the sides, and blowing out the top....made a terrible whining noise

 

[CamaroGuy]

Okay,

I just called a tech guy at Alpha-Novatech and asked him to explain to me the best installation scenario: suck-in or suck-out. The guy said, "induction"!?

I then had him explain to me what exactly he meant by "induction" and it appears that I was mislead originally by the info listed on their Q & A page (which I'll paste below for reference).

Which type of fan heat sink is better, "expulsion type" or "induction type"?

According to our tests, the induction type showed better results the the expulsion type. This is because we used an intake cover to draw air through the lower part of the heat sink for more heat dissipation from the lower part of the fins. However, if some other heat source is located near the heat sink, heated air would come into the heat sink and affect the thermal performance, so the choice must be made depending on the environment.


They use the term "induction" to mean inducting air through the fins and up and out of the fan--therefore sucking-out. Conversely, they are using the word "expulsion" to mean expulsing air out through the heatsink--basically sucking-in from the top and blowing out the fins.

I think they should have reversed their terms though, because logically, in my opinion, I read "induction" to mean inducting air into the heatsink through the fan (from above), and expulsion to mean taking the air out away from the heatsink. I guess it just matters which way you look at it though.

So to sum it all up, we should use what they call "induction" when assembling our alphas. I think we all agree that this means "sucking-out" or blowing air out away from the heatsink, not onto it.

Hope this helps to settle the issue.

-CamaroGuy

 

[slunk]

I have a fan mounted on the side of my case, blowing cool air towards my Duron and Alpha6035. Would it be better to have the fan, that is attached to the heatsink, blowing the air towards the heatsink rather than away in this case?

collin

 

[Lore]

I had mine set to sucking OUT (that is, the fan blows out the top) and it made a terrible whining noise and didn't seem to cool as well. I reversed it - had the fan blow _onto_ the heatsink and it worked much better. It's quieter, too.