Quick heatsink fan question.

[nan0_man]

should the fan be blowing into the fins of the heatsink of sucking air away from said fins?

I would go with 'sucking away from', but the one i'm looking at, (gateway P4, never been internally altered by owner, I'm re-installing his O/S for him), has the fan 'blowing air into'.

SUCK!

...or blow?

[gvblake22]

...Blow
The fan should almost always blow down onto the HS at the processor.

There's only a couple of the thermalright heatsinks that SOMETIMES have slightly better performance with a fan sucking instead of blowing, but even that depends on your case airflow.

[nan0_man]

reallllly?

[gvblake22]

reallllly?
LOL
YES, really!
haha, why would I lie to you?!
*Love thy fellow OC forums member!* :beer:

Someone wanna back me up here?

[nan0_man]

surely it would be better to draw the hot air away from the processor in apose to blowing it back onto it?... no?

truely perplexing.

[gvblake22]

like I said, sometimes it does actaully work better to suck the air away from the HS, but that is only true for a limited number of cases.
The thing that makes for better performance with the fan blowing down onto the HS is that its really the air pressure from the fans that cools the fins on the HS, not so much the fact that the moving air around the fins is removing the hot air being dissipated by the fins.

Its kindof like when you are trying to cool a bowl of soup. indstead of trying to "suck" all of the hot air from around it, you blow cool air on it to actually cool the material (soup). Well, its *sort-of* the same with a heatsink. The main reason why sucking doesn't work well is because there is not very much room in or under most HS's for the fan to actaully suck air from; its like putting a large box fan against a wall and wondering why it is not blowing air out into the room very well.

See, the heat from the processor is transfered through the base of the heatsink out to the fins where the surface area is increased and there is more cool air around for the heat to dissipate to. So you are not necessarily trying to remove the heat from around the fins of the HS, you are really trying to actaully cool the fins of the HS so the whole thing will be cooler.

Heatsinks work by transfering heat from the CPU core up through the heatsink out to the fins, thus increasing the surface area of the heated component and cooling it. The aluminum or copper of a HS can only really hold SO MUCH 'heat' so when the cpu heats up the heatsink close to the point where the HS cannot really 'hold' any more heat, the transfer of heat from the cpu to the HS stops and the CPU starts getting hotter instead of the HS (which as you probably already know is a BAD thing;) )

[RangerXLT8]

I concur.

[Mr. $T$]

gvblake22 is right. Also some Thermalright sinks have large overhangs on the sides to allow some air to be directed to cool the NB and voltage transistors as well.

[gvblake22]

I concur.
gvblake22 is right. Also some Thermalright sinks have large overhangs on the sides to allow some air to be directed to cool the NB and voltage transistors as well.
LOL, thank you! :burn:

[Mr. $T$]

LOL, thank you! :burn:


When your right, your right :D

[nan0_man]

im so glad i asked, i can see clearly now, you learn something every day.

thanks guys!

[David]

It depends on your case - I dropped a few Cs when i changed mine to suck. But 90% of the time, blowing is better than sucking.

Anyone who quotes that out of context will get a slap ;)

[Kid Payne]

LOL
YES, really!
haha, why would I lie to you?!
*Love thy fellow OC forums member!* :beer:

Someone wanna back me up here?


Very true! I've never had a HSF that sucks. I've fans that suck, but none that sucks the air, but like gvblake22 said there are a few out there that sucks the air.

[@md0Cer]

Some of the older Alpha heatsinks worked better with the fan sucking air through them. For a majority of heatsinks, the generally work better with the fan blowing through them, especially the SLK, ALX, and SP designs from Thermalright. With the way those heatsinks are, without a duct of any sort, sometimes the fan hangs over the edges of the heatsinks, and you end up sucking air from outside the heatsink and not through. Either way, I have tested it on my SLK-900 and I had higher temperatures both idle and load.

I recomend you test it out on your heatsink and just go with whatever works best. Keep in mind for accurate test results to try the two different ways at as close together time-wise as possible to rule out any ambient temperature/condition changes that would mess up your test results.

[RangerXLT8]

It depends on your case - I dropped a few Cs when i changed mine to suck. But 90% of the time, blowing is better than sucking.

Anyone who quotes that out of context will get a slap ;)

LOL!!!!!!! that's great

[hibner]

rofl, This thread is hillarieous...... suck, blow, suck, blow:burn:

[aNTiChRisT]

Its not out of context, its just missing... parts...

:D

~t0m

[nan0_man]

Thanks guys, I appreciate the input.
I will test and let you know the results. I have a digidoc which i'll put a sensor at the base of the sink as close as I can get to the CPU.
My fan by the way, is actually smaller than the heatsink so I'm wondering if I should change it out for him??


This now poses another 'Suck/Blo' related question. Should my stealth be sucking air thru my corvette heatercore, as it is at present?
IT would really suck if sucking blowed when it comes to cooling the heatercore! And my fan/shroud/core are pretty permanently affixed.

[gvblake22]

IT would really suck if sucking blowed when it comes to cooling the heatercore!
LOL!! Thats great!

Sorry though, I can't answer that one for sure, not very firmiliar with water cooling:( Just had to comment on that wonderful quote!! :D :attn: