Andrewza

I have this:

Firmly attached to the top of my athlon xp 2200 with an 80mm ys-tech blowing down into it and the CPU temp reads mostly between 3-5 C above motherboard temp, so I'll assume it's working

Thinking about most HSF I've seen on conventional PCs, they seem to be designed so the fan forces air through the heatsink i.e. through the fan, then the heatsink, otherwise the air would come from the easiest source and not pass over most the heatsink. I could be wrong though.

[Edited by Andrewza - 11/4/2002 2:16:31 PM]

Mr Footlong

iTrader: (7)

Yes, but the Zalman flower was designed with air being blown through it in mind, that's all that I am saying. It is not like a normal heatsink in the way that if you reverse a fan on a heatsink, it is pulling virtually all of it's air through the heatsink fins. The Zalman fan mount design is completly open, floating and not directly attached to the heatsink in any way whatsoever, therefore, is not as efficient unless the design is modified.

Cheers,

Nick

[Edited by Mr Footlong - 11/5/2002 9:11:48 PM]

Mr Footlong

iTrader: (7)

FREE FLOWING, not charged directly through the fins, so even though the 120mm fan will most likely be flowing more cfm's than the standard 92mm, it is spreading it across a larger surface area and is not be forced directly through the heastink fins to escape mate.

So unfortunatly, perfectly understanderble. I changed from a 92mm to a 120mm back when I was on zalmann's, not to decrease temps, but to run the fan more silently It also helps with how well you position the Zalmann fan above the heatsink and how well the exhaust system works on your rig. Mine did drop 2 degrees(Yey, a whole 2!) with the 120mm tho.

Yawn, anyway.....


Cheers,


Nick

[Edited by Mr Footlong - 11/5/2002 11:24:18 PM]

Luke

What should it be doing??

suba

should be blow. most heatsink blow (from top blowing into the heatsink) although some heatsink suck, all depends on the spec/design of the heatsink.

Chris_S199

Most CPU fans draw air away from the heat sink. The idea is that cold air is drawn through the sides of the heat sink and then up away from it by the fan. The exhaust fans in the case are then responsible for pulling in cold air (bottom front of the case) and expelling warm air (top rear of case). At least that's how I understand it...

AlexM

The vast majority of Heatsinks are designed for the fan to blow air down through the heatsink towards the processor. This is to ensure that the maximum amount of ambient air is directed down to the center of the heatsink, which is where the maximum temperature occurs.

Running the fan in the opposite direction usually means that air is drawn in around the edges of the heatsink, and there is very little airflow across the core area, which will raise the temperature of the CPU.

This is easy to prove experimentally - just compare the BIOS readings for CPU temperature with the fan operating normally and reversed.

Cheers,

Alex

P1Fanatic

Most cpu fans suck off as if you put your hand over it you can feel the warm air being expelled. You use the case fans, as someone has already said, to suck in colder air and expel the warmer air.

suba

i think it's all depends on the design/spec of the heatsink from the manufacturer whether to suck or to blow!

Eagle7

most blow down, though some are starting to suck.

the 'suckers' usually will explicitly say that they are meant to suck through, and may have enclosed sides so that air comes from the bottom of the heatsink instead of just coming in the sides and up.

Check your instructions for this. I have read an article where they tried reversing the flow on certain heatsinks and it can dramatically reduce the cooling performance if you get it wrong for your sink.

FERRARINUTTER

Taken apart my Pc AT THE WEEKEND AND BOTH MY ATHLON 1.6 & pENTIUM 2.8 BLOW DOWN ONTO THE HEATSINK.........

suba

this blow and suck thing is getting exciting!

luke, are you sure it's about the CPU fan and not something else???

Fig

Blow 5 - 2 Suck so far

any more takers?

FERRARINUTTER

I'm always up for a blow, me getting not giving, AHEM of course......

kamikaze

sucky sucky

suba

blow blow blow!

Mr Footlong

iTrader: (7)

Shows how many of you have built pc's before!

By a huge proportion, heatsinks have air charged down through the fins and out through the sides of the sink.

A few maunfacturers make either suck through heatsinks or 2 way capable, a la Alpha.

The suck through designs have been used before by people like Dell on some models to good effect and they may well still do this, but they usually have a fancy plastic channel going from cpu to the exhaust fan on the back of the pc.

Cheers,

Nick

DominicA

i believe the Zalman flower to be the most common reason for people sucking rather than blowing, this can be used to very good effect when combined with a side panel vent/fan....

as you say, the Dells do suck...

Mr Footlong

iTrader: (7)

I have had a lot of zalmans and unless you build some kind of channeling around them, then they are not quite as effective as blowing in my experience.

Cheers,

Nick

suba

with the zalman, you cant blow much as it will only re-circulate the hot air inside the case, hence need a good suck with vents/ducts to get hot air out.

similar to DELL, the fan on the case give it a good suck via the ducts all the way into the heatsink/CPU.

so, blow or suck? it's all in the design

Attu

Looking at the 8 cpu fans ive got next to me (dont ask ) its blow, ive tried the other way and havnt found much difference but every heatsink/fan ive bought has been blow..never mind feeling if its blowing look at the arrows on the side of the fan

Andy

super_si

With the Zalman i used a 12cm fan and make no difference at all!

Si

super_si

Mine didnt make much difference!!

I knocked the power to the fan out once by accident, the heat sink was roasting!! it reached 80!!

Till i noticed what i'd done