Options
Cooling fans... again.
Si_Crewe
Posts: 40,202 Forum Member
✭
So, as you might already know, I'm a bit obsessive about the cooling of my PC, largely as the result of needing a PC which can sit on a shelf, which means using a micro-ATX mobo and case.
Anyway, having decided to junk my internal DVD drive, there's more space in the case which means, in turn, that I can reduce the number of fans in my system (currently nine) and replace them with 6 larger, slower, quieter fans. 2 x 120mm inlet and 2 x 80mm + 2 x 40mm discharge.
My mobo has outputs for a chassis fan, case fan and something which Asus call a Q-fan.
Thing is, the chassis fan and case fan are constant speed fans whereas the Q-fan can be set to change speed to compensate for temperature changes.
So, basically, the question is this: Am I better having the variable-speed fan drawing air INTO the PC or am I better using it to extract air FROM the PC?
My first thought is that it'd be better making the inlet fans adjustable so that, if the temperature rises, more cool air gets drawn into the system and any additional air, which the discharge fans can't handle, would just exit through the case vents.
Thing is, OTOH, my inlet fans are a pair of 120mm fans so chances are that they'll always be pumping in more air that my discharge fans (2 x 80mm and 2 x 40mm) can extract.
That being the case, it might actually create better air flow if the discharge fans are the variable speed ones so that, if the temperature rises, they'll speed up and there'll be more air flow through the system.
Yeah, I know I probably obsess over this stuff way too much (especially since I don't actually have any particular overheating issues) but I just like to try and do things the best possible way.
So, basically: Variable-speed inlet or variable-speed discharge? Anybody got any opinions?
Anyway, having decided to junk my internal DVD drive, there's more space in the case which means, in turn, that I can reduce the number of fans in my system (currently nine) and replace them with 6 larger, slower, quieter fans. 2 x 120mm inlet and 2 x 80mm + 2 x 40mm discharge.
My mobo has outputs for a chassis fan, case fan and something which Asus call a Q-fan.
Thing is, the chassis fan and case fan are constant speed fans whereas the Q-fan can be set to change speed to compensate for temperature changes.
So, basically, the question is this: Am I better having the variable-speed fan drawing air INTO the PC or am I better using it to extract air FROM the PC?
My first thought is that it'd be better making the inlet fans adjustable so that, if the temperature rises, more cool air gets drawn into the system and any additional air, which the discharge fans can't handle, would just exit through the case vents.
Thing is, OTOH, my inlet fans are a pair of 120mm fans so chances are that they'll always be pumping in more air that my discharge fans (2 x 80mm and 2 x 40mm) can extract.
That being the case, it might actually create better air flow if the discharge fans are the variable speed ones so that, if the temperature rises, they'll speed up and there'll be more air flow through the system.
Yeah, I know I probably obsess over this stuff way too much (especially since I don't actually have any particular overheating issues) but I just like to try and do things the best possible way.
So, basically: Variable-speed inlet or variable-speed discharge? Anybody got any opinions?
0
Comments
Sometimes simple is better.
It matters not if the fans blow into the case or suck air out of the case.
What is important is the airflow THROUGH the case and the route that it takes. It is necessary to sort out where the air enters the case, where it leaves the case and the route through the case i.e over all the hot spots collecting the heat as it goes.
Normally it is considered best to enter the case at the front/bottom and leave the case at the top/rear. Where it goes in the case can be 'guided' by positioning the components and/or baffles or guide barriers.
If done correctly much heat can be removed by natural ventilation without the use of fans at all. However most PCs will need fans to speed up heat removal.
Remember that the fan merely assists the airflow.
Having a single fan, say of 100 Cu Ft/min, will ensure that that amount of air will flow through the case per min. It matters not where the fan is located, sucking in or blowing out.
Having 2 fans, one on the inlet, one on the outlet you will still only have 100 cu ft /min flowing through the case. But if BOTH fans are on, say the back, you will have 200 cu ft/min airflow.
You MUST locate the fans so that they work together and re-inforce the airflow through the case. 2 fans fighting each other will achieve nothing.
Designed correctly, the air will flow freely with very little fan assistance required meaning that you can use variable speed fans to run only as fast as necessary.
And sometimes more complex solutions are required.
This is one of those times.
As supplied, the cooling in my case is rather marginal. There's a single fan at the front and 2 small ones at the back.
Once you've got HDDs and a DVD drive installed, the front fan is pretty-much obstructed and, as a separate issue, air flow from front to back does little to cool a video card which is wedged up against the side of the case.
This bit is wrong.
This bit, impressive as it is, is nothing to do with what I asked.
In all the years I have been using a building computers, big ones, small ones, only one person i know that have a load of fans in his case and that was only because they was built in. He does a lot of gaming and get a pretty large video card.
Some people do go over the top with cooling, I even built one machine with one fan, and that cools the CPU as well.
What CPU are you using and what case? Then maybe people will get a better idea.
Set your shutdown temperature in BIOS, mine is IIRC 70c
Stop looking for the solution to a problem that may well not exist.
I agree with you there.
http://www.techspot.com/article/927-temperature-impact-cpu-performance/
Kindly explain.
I will summarise what I said to help you understand.
"Get the airflow right then use variable speed fans to reduce noise when maximum cooling is not required"
Temperature sensor controlled fans, higher pressure fans, are obviously more use on CPU and GPU heatsinks.
Case fans are more about volumes of air shifted, preferably input fans are dust filtered and a positive pressure in the box should help to keep out dust.
Not knowing the case concerned, flow routes, fan characteristics, impossible to make much detailed comment.
Modern ASUS boards seem to have a lot of fan profiling available for twiddlers of the unknown.
The OP shouldn't need 9 fans for a non o/c rig. If he is overclocking, then he should be using a larger case. In fact most o/c ready mobos are ATX. Also I've never seen a mATX case that could take 9 fans. I've got some quite large Antec 300 cases that only have room for 5 fans. Something don't add up here.
Also more fans = more fluff inside the pc = overheating . . . or maybe I should vacuum my flat a bit more often . . .