Should computer fans suck or blow?
Discussion
Simple answer "depends".
Complex answer "depends."
You can devise really complex cooling systems for PC's using positive or negative pressure (i.e. all the fans empty air and vents bring in the cool or vice versa). Generally speaking however what usually happens is that the front fans draw air in (suck) and the rear fans extract (blow).
Fans on the side generally bring air in and if you've added a blowhole to the top then it will be uses as an additional extractor. I have seen a few people who are handy with a Dremel add intakes at the very base of the systems as well.
If you really want the best cooling though it's time to drop air and move to water, but that seems to be more of a geek/hobbiest thing (water cooled AMD64/ Nv5950U pulling PVR/media duty here).
Complex answer "depends."
You can devise really complex cooling systems for PC's using positive or negative pressure (i.e. all the fans empty air and vents bring in the cool or vice versa). Generally speaking however what usually happens is that the front fans draw air in (suck) and the rear fans extract (blow).
Fans on the side generally bring air in and if you've added a blowhole to the top then it will be uses as an additional extractor. I have seen a few people who are handy with a Dremel add intakes at the very base of the systems as well.
If you really want the best cooling though it's time to drop air and move to water, but that seems to be more of a geek/hobbiest thing (water cooled AMD64/ Nv5950U pulling PVR/media duty here).
Edited by thepassenger on Friday 21st July 21:18
So ...
it seems the world is undecided then?
I can see the point of heat/air flowthrough but as I (like most) have it under a desk perhaps it would be better to suck** out of the front as well?
**sorry extract
>>>>Update
I have stuck a thermal probe into the case and its reading about 34C. External room is reading 28.5C so is that OK?
it seems the world is undecided then? I can see the point of heat/air flowthrough but as I (like most) have it under a desk perhaps it would be better to suck** out of the front as well?
**sorry extract
>>>>Update
I have stuck a thermal probe into the case and its reading about 34C. External room is reading 28.5C so is that OK?
Edited by scared but happy on Saturday 22 July 16:04
scared but happy said:
I have stuck a thermal probe into the case and its reading about 34C. External room is reading 28.5C so is that OK?
one of the two self built servers in my office runs at about 47degrees internally. the other runs between 34 on a cold day and 54 on a very hot day (although its side is now removed and runs constantly at between 42 and 44).
34 shouldn't be a problem.
They key really is getting good airflow. IME any side fans, blowholes and the like just bugger that up. The reason for pulling air in at the front and pushing it out of the back is because the typical tower case has space for fans lower at the front; as hot air rises you want to extract from the higher point.
Keep an eye on temperatures but there's no point going overboard, as long as they're not excessive in this weather then it'll be fine.
Keep an eye on temperatures but there's no point going overboard, as long as they're not excessive in this weather then it'll be fine.
The main reason for thinking about where the fans sit and whether they suck or blow is that you need to get the cool air to actually pass over the hottest components on its way through the case, or else its just a pointless exercise!
Q: In your fairly typical setup with a tower under the desk, where's the best source of cool air?
A: The room.
Therefore, suck it in from the front and exhaust it at the back. Yes, it'll get hot behind your desk but who cares?
If you're really worried about it, tidying up the cables inside the box (especially any flat ribbon cables) so that they're not impeding the airflow can make a huge difference. I used to have terrible trouble with heat, as the PC lives in the loft room and the room gets stupidly hot in this kind of weather. Ths year I added an extra inlet fan at the front of the case and changed all the flat ribbon cables for round ones and even though the ambient temperature in the room is higher than ever before the PC is hanging in there.
Q: In your fairly typical setup with a tower under the desk, where's the best source of cool air?
A: The room.
Therefore, suck it in from the front and exhaust it at the back. Yes, it'll get hot behind your desk but who cares?
If you're really worried about it, tidying up the cables inside the box (especially any flat ribbon cables) so that they're not impeding the airflow can make a huge difference. I used to have terrible trouble with heat, as the PC lives in the loft room and the room gets stupidly hot in this kind of weather. Ths year I added an extra inlet fan at the front of the case and changed all the flat ribbon cables for round ones and even though the ambient temperature in the room is higher than ever before the PC is hanging in there.
I have tried sucking front, blowing back but it gets VERY hot under the desk (in a corner/next to wall). I have also changed the cables to those funky round ones to help with the air flow. But I will say that I have now moved the extraction fans to the top of the PC and this has helped (thanks). I am now wondering if I need a huge one on the side to help as well.
BTW if they need to extract heat as much as possible from major components it does seem daft to have the computer motherboard on its side and also its the wrong way round if you think about it as the plug in boards (for example) the Nvidia graphics card has a fan, BUT its underneath! If the heat rises it will heat the board up so how can I dissapate the (trapped) heat?
BTW if they need to extract heat as much as possible from major components it does seem daft to have the computer motherboard on its side and also its the wrong way round if you think about it as the plug in boards (for example) the Nvidia graphics card has a fan, BUT its underneath! If the heat rises it will heat the board up so how can I dissapate the (trapped) heat?
my 2p worth....
I was suffering huge heat problems with the Intel CPU going into slowdown to save itself all the time, even when cool in the room. At the time I just had a crappy 120 low flow fan extracting at the back. So I replaced it with a higher airflow 120, added a low airflow at the front blowing over the hard drives then into the case, then another low airflow in the side over the graphics card. Brought the temp down in the PC nicely so it stopped overheating but CPU was still running very hot. Ended up putting an arctic cooling CPU cooler in (only £25!) now CPU runs cold all the time (or near as anyway).
Low flow fans used as they are quieter - and the arctic cooling fan is virtually silent.
I was suffering huge heat problems with the Intel CPU going into slowdown to save itself all the time, even when cool in the room. At the time I just had a crappy 120 low flow fan extracting at the back. So I replaced it with a higher airflow 120, added a low airflow at the front blowing over the hard drives then into the case, then another low airflow in the side over the graphics card. Brought the temp down in the PC nicely so it stopped overheating but CPU was still running very hot. Ended up putting an arctic cooling CPU cooler in (only £25!) now CPU runs cold all the time (or near as anyway).
Low flow fans used as they are quieter - and the arctic cooling fan is virtually silent.
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