Suck or blow?

[tgpo]

I look around for TGPO when I need alot of hot air blown out of my case.

And I do it so well!

[kyemeng]

If you are extracting the air, the fans should be sucking as in the case of fans placed at the rear. In the front, they should be blowing so as to bring fresh, cold air in.

For the CPU or individual peripherals, blowing air at it may be better than sucking. Well, if you are standing in front of a fan, would you rather it be sucking or blowing air at you?

[ROF]

If you are extracting the air, the fans should be sucking as in the case of fans placed at the rear. In the front, they should be blowing so as to bring fresh, cold air in.

For the CPU or individual peripherals, blowing air at it may be better than sucking. Well, if you are standing in front of a fan, would you rather it be sucking or blowing air at you?

I think you have your first two sentences reversed. suck = exhaust; blow = vent. When it comes to your position in relation to the fan it depends on what you are attempting to achieve. I have never attached a CPU fan upside down(air blowing towards the core).

[Almost Human]

ROF, after installing 60+ CPU heatsink/fan combo's I have yet to see one that did not blow onto the CPU heatsink. All of the separate units I put together were blowing onto the heatsink.

[Marty2003]

ROF, after installing 60+ CPU heatsink/fan combo's I have yet to see one that did not blow onto the CPU heatsink. All of the separate units I put together were blowing onto the heatsink.

I'll have to agree with that. It is a lot more efficient to have a fan blowing onto the heatsink than away from it. If you buy a cooling fan from wal-mart to keep cool during the summer, do you stand behind it so it sucks the heat away?

[ROF]

ROF, after installing 60+ CPU heatsink/fan combo's I have yet to see one that did not blow onto the CPU heatsink. All of the separate units I put together were blowing onto the heatsink.

I'll have to agree with that. It is a lot more efficient to have a fan blowing onto the heatsink than away from it. If you buy a cooling fan from wal-mart to keep cool during the summer, do you stand behind it so it sucks the heat away?

Try this sometime on those hot summer days. Close all your windows and put two or more fans in your windows blow air out of the house. After a few hours check the temperature in the house. On the next day when the temperature outside is relatively the same degree reverse the direction of your fans. On both days, which house is kept cooler?

I have heard many different pros and cons for air flow in both directions for CPU fans. They both make sense in my opinion which was why I only trust my own experiences. I did an experiment almost a decade ago using socket A motherboards with identical cases and components. The heatsink was considerable(+10 degrees) cooler when the fan was sucking air up and away from the heatsink as opposed to blowing hot case air onto it.

In relation to manufacturer or factory assembly has anyone here bought a CoolMAX or AOpen case with fans? How was the rear exhaust fan pre-installed? Mine have all been blowing air into the case. Kinda defeats the purpose of calling it an exhaust fan in my opinion.

[jman98]

I just have to say that this is the best subject title ever for a discussion on this forum! I wish there was a Hall of Fame where we could enshrine this entry for the ages. It was funny, clever and accurate.

[DarrellS]

I've heard that before about having a top exhaust. Probably the best way as heat rises, but most people don't want the noise of a fan blowing out the top. You could check the temps near the top of the case. In all the computers I've assembled, the PS fan sucks out any warm air near the top, so that idea doesn't seem worth the effort.

The problem with using the power supply fan to get rid of the top heat is that the power supply is already hot and this could lead to premature PS failure. I've seen expensive cases with the power supply in the bottom of the case in a special compartment, away from the heat.

I also have a problem with some cases blowing air into the CPU cooler from the side. If the fan doesn't have a filter on it, they tend to blow all the dust in the air directly into the CPU cooler, which may cause problems in the long run. The front intake fans don't seem to have that problem.

I have a horn on the side of my case and the CPU fan sucks the hot air from the CPU out of the case. I don't use a fan to blow air onto the CPU.
A few people mention that CPU fans blow air onto the CPU but if I stick my hand in front of the horn, I can feel the hot air exiting from the CPU at a decent rate like the CPU fan is blowing the hot air out through the horn (well, it's pretty cool right now since I put a good window air conditioner in my computer room and have the two front fans helping to keep things cool. I'm only surfing the internet now though and not doing anything CPU intensive).

I assume that the heat sink radiates the heat away from the CPU and the fan forces the heat away from the processor where it can be drawn out from the rear exhaust fan or whatever other exhaust fans you may have.

[SingSing]

I look around for TGPO when I need alot of hot air blown out of my case.

And I do it so well!

TGPO is already full of hot air, you guys are going to cause global warming.

[Alan69]

ROF, after installing 60+ CPU heatsink/fan combo's I have yet to see one that did not blow onto the CPU heatsink. All of the separate units I put together were blowing onto the heatsink.

I'll have to agree with that. It is a lot more efficient to have a fan blowing onto the heatsink than away from it. If you buy a cooling fan from wal-mart to keep cool during the summer, do you stand behind it so it sucks the heat away?

Actually from an efficiency standpoint, it's more efficient to suck than to blow, for similar reasons that it's more efficient to pull than to push. Blowing against something like a heatsink creates back pressure and reduces airflow. Same fan sucking air through a properly designed heatsink will simply move more air. It'd have to be well designed and have proper ducting though, to bring that air into contact with a lot of the surface. Cheaper and easier to make a simple straight vaned sink and blow at it..

And you have the side case fan and others in most cases. In connection with the rest of the system it simply makes sense to go with the flow and do what everyone else does.


And of course, it's always better to have multiple fans doing different things, just ask Gene Simmons..

[vhelp]

Ok. Here are my explanations and reasons why I am at opposite with
you all. And these are all based on my own actual experiences.

The thing is.. you have a case that incloses a very small tight area.
And, add to that, that the air inside the case is full of hot air from
the various components (heat sinks and diods and other i/o boards that
collect and/or produce heat w/ their own components. All of this is
adding to the heat building up inside the case. The key point here is
the small foot print space.

Now, someone says that its recommended that we setup our CPU fan to
blow onto the cpu heat sink, this collected heat from inside the case.
Now, even though you have a fan blowing (or, sucking) air OUT of the
case (from the rear) I can not say that that is enough to warrant the
CPU fan to be applied (in my opinion) reversed -- blowing onto the CPU.

Oh, but wait.. there is another factor in this. In my experience with
CPU and case and fans, etc.. I alway have accumilation of caked on dust
that is very think like a blanket or something. This gets "wedged" between
the CPU 's fins, and consiquentially, guess what happens ??
Hopefully, you guessed correctly. << More heat >>

Some of you might say, well, you did have proper ventalation. I say,
hogwash. I have made plenty of home-brew cpu kits in my time (and, I'm
tired of mak'en 'nem) and sooner or later, pending weather and age, the
cpu or motherboard gives out. If you catch it in time, (during spring-
cleaning) you'll find the talked about dust build-up wedged inside the cpu
heat sink fins. Now, some homes or apts are more dusty than others. So,
I'll consider that a factor. But, that does not dismiss why *I* need to
reverse polarity of the fan in my situation. I can tell you that aprox
every 3 months or so, I have (had) to clean out my cpu heat sink fins of
this dust. But, that was in the past. So far, this year, I have yet to
clean the heat sink fins, not to mention a noticable *decrease* in cpu
temperature. In addition, you'll noticed that your cpu fan is usuing
less energy, because the constricking air-flow (distance) to the cpu
block is not hard at work, SUCKING you hard hehe..

Here's what I would like to suggest to those that are willing to test their
inviornment situation. Look inside your cpu and observe for any dust.
If there are, then you stand a better chance at reversing your cpu's fan's
polarity -- IOW, turn your fan around

-vhelp 4094