help me settle a question with my friend...

[Jeff Bolton]

for the longest time i had my delta fan blowing down onto the heatsink. my friend tells me that it should be blowing off of the heatsink. it makes more sense that way because with the finger guard facing up (so i don't gnaw a finger off) the fan is blowing up away from the HS. but i don't know for sure. on a similar note, when i start to build my new box this christmas, i'm planning on getting a couple of 92mm's for the side. should they be blowing both in, both out, one in, one out, or what? thanks for the input guys..

jeff

[nihili]

There is no right answer to which way the fan should blow. The best thing is to try it both ways and see which cools better. The results can be different even on very similar setups. In my rig, I do better sucking off the heatsink when I'm moderatley overclocked. But I do better blowing on to the heatsink with a heavy overclock. Go figure.

In general you want the intake and exhaust of your case to be balanced. Some people prefer a slight negative pressure, some prefer a slight positive pressure. If you're ductuing, you want a slight pressure in the direction that will assist your duct (positive for exhaust, negative for intake). Other than that, the only convincing argument I've heard is that if you filter your intake fans and maintain a slightly positive pressure, you won't have to worry about dust.

THe most important thing though is airflow. You want to set your fans so that air flows through your case freely rather than getting caught up and forming eddies. Without proper airflow you can get stagnant air around your heatsink. In that case it doesn't matter how big a fan you put facing which direction on the sink. Since the air just recycles through the sink, it just gets hotter and hotter.

nihili

[Silversinksam]

'There is much wisdom in that thar beard of Mr. nihili'



Gotta add to this to his excellent info:

Generally if the heatsink has a shroud it may do better to suck

No Shroud and the fan should blow....

But like nihili said there is no right or wrong way as your milage may vary.



:burn:

[Silversinksam]

Originally posted by Spike Spiegel
it makes more sense that way because with the finger guard facing up (so i don't gnaw a finger off)
jeff


Ps the wire fingerguard will screw onto both sides of most fans

:burn:

[zap3v]

I read a post a few days ago about someone having trouble with cooling in their Antec SX800 series case. They found out the problem was that the dual exhaust fans were conflicting with the fan on the heatsink in that they were choking its ability to blow down onto the heatsink. When he reversed it to blow OFF, it cooled much better. OK, so I had mine blowing ON as I thought was standard and as the direction on my heatsink said. I tried to reverse it and got worse temps. Same mobo temps but 2-4 degrees greater when I had it blowing OFF. Same case, same fan, and maybe even the same mobo from what I remember of the post. No logical reasoning here, but I have the temps to validate my findings. It was easy to do anyway certainly not something that is too frustrating to try. I could remove my heatsink fan in a few seconds with the heatsink totally intact still with no removal of anything. When in doubt, try it yourself. It's fun.

[The Overclocker]

if you want your fan to suck to take advantage of the lower noise use tape to have a skirt around the heatsink agout 2/3rds of the way down focing air to come in at the bottem

[Thelemac]

Just remember that when you test your new temps that you don't have as much air blowing onto your motherboard anymore...which can easily affect the temps as read by the insocket thermistor. It might look like you're doing better or worse when the oposite is actually true.

[Jeff Bolton]

i actually have about as good temps now (at 1333) with the fan blowing off then i did at 1300 with the fan blowing on and the same case temps. so its all good. thanks for all the input.

jeff