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Side fan airflow question
- Thread starter pestul
- Start date
- Joined
- Sep 5, 2002
- Location
- Boise, ID
Nooooo, you want the hot air out of the case. It's best to have the intake fans at front bottom to draw in cool air in to the case and the exhaust fans at the back, at the top and also at the side. This way you have a smooth flow of air through the case.
The cold air comes from the front bottom, it rises as it heats up and then gets exhausted from the back, the top and the side panel.
If the side panel fan is at the same level as the CPU fan, you could try reversing the CPU fan so that it also draws air out instead of pulling air in. That way, the hot air from the heatsink would be pulled away by the CPU fan and then it would be exhausted by the side panel fan.
The cold air comes from the front bottom, it rises as it heats up and then gets exhausted from the back, the top and the side panel.
If the side panel fan is at the same level as the CPU fan, you could try reversing the CPU fan so that it also draws air out instead of pulling air in. That way, the hot air from the heatsink would be pulled away by the CPU fan and then it would be exhausted by the side panel fan.
A buddy of mine has done a mod with reverse airflow on the side fan.
That because his side fan was direct over the CPU heatsink. He dismounted the stock CPU heatsink fan, and set the side fan to max and let it blow air from outside directly onto the heatsink, with surprisingly good results. The CPU temps fell about 5 c's.
But it really depends on where your side-fan is, and how the airflow in your case is.
Cheers, Flix
That because his side fan was direct over the CPU heatsink. He dismounted the stock CPU heatsink fan, and set the side fan to max and let it blow air from outside directly onto the heatsink, with surprisingly good results. The CPU temps fell about 5 c's.
But it really depends on where your side-fan is, and how the airflow in your case is.
Cheers, Flix
- Joined
- Nov 6, 2002
pestul said:
If that sidemounted fan is right around the level of your CPU HS fan...then yes you should have it blow in...it will bring the cooler outside air directly to the CPU fan whihc in turn will let the CPU cool better by NOT using the hot system air to try to cool it...
I have 2 side mounted fans...one blowing directly over the CPU and the other blowing directly over the AGP...this way the VC and CPU both get cooler outside air to cool...
- Joined
- Nov 6, 2002
- Joined
- Sep 5, 2002
- Location
- Boise, ID
Re: Re: Side fan airflow question
Eh but then, if you reverse the CPU fan, it is no longer using the hot air inside to cool the heatsink. Then it is taking the hot air away from the heatsink and if you have a side panel fan just at the level of the CPU, the air the CPU fan is pulling would be quickly exhausted out of the case.
IF the blowhole is at the same level as the CPU, it should be kinda high, right? And since the hot air rises and you need to exhaust it, I think it's better to push the air out of the case rather then pull air in. After all, I'm sure we would all agree that it's not a good thing to push air into the case from the top because the hot air would want to exit from there.
The same way, if you try to blow cooler air onto an area where there is a flow of hot air, wouldn't that create turbulance there?
EDIT: I think it makes sense to pull air into the case from a hole at the same level as the graphics card because that is closer to the bottom of the case. When you do this, the air there will get hot because of the graphics card, rise up and then the exhaust fans would get rid of it.
I just say pull air from the bottom and exhaust at the top.
glock19owner said:
Eh but then, if you reverse the CPU fan, it is no longer using the hot air inside to cool the heatsink. Then it is taking the hot air away from the heatsink and if you have a side panel fan just at the level of the CPU, the air the CPU fan is pulling would be quickly exhausted out of the case.
IF the blowhole is at the same level as the CPU, it should be kinda high, right? And since the hot air rises and you need to exhaust it, I think it's better to push the air out of the case rather then pull air in. After all, I'm sure we would all agree that it's not a good thing to push air into the case from the top because the hot air would want to exit from there.
The same way, if you try to blow cooler air onto an area where there is a flow of hot air, wouldn't that create turbulance there?
EDIT: I think it makes sense to pull air into the case from a hole at the same level as the graphics card because that is closer to the bottom of the case. When you do this, the air there will get hot because of the graphics card, rise up and then the exhaust fans would get rid of it.
I just say pull air from the bottom and exhaust at the top.
OP
- Joined
- Dec 19, 2000
- Thread Starter
- #8
Well, interesting results to say the least.. I was actually wrong about the windowed-fan, it was in fact blowing air in initially (from graphics card level). I reversed it anyway for something to do, not a whole heck of a lot of difference. It might actually be 1-2C (cpu) cooler blowing out, which surprises me due to normal expected airflow patterns. Case temp appears to have gone up 2-3C, meaning likely that the cpu heat is being dissipated well, but there isn't enough cool outside air coming in for the rest of the components. Odd to say the least..
I have a side panel fan blowing onto the CPU. The fan is positioned pretty much on top of the CPU. This fan blows cool air in while the 2 rear exhaust and the PSU exhaust fan suck the heat created by the CPU out.
Your case temps are probably rising b/c the case temp sensor is somewhere near the bottom. And the heat doesn't get exhausted until it reaches your exhaust fans. I'd say to leave the fan blowing in so that the video card doesnt create as much heat which eventually rises to the CPU.
Your case temps are probably rising b/c the case temp sensor is somewhere near the bottom. And the heat doesn't get exhausted until it reaches your exhaust fans. I'd say to leave the fan blowing in so that the video card doesnt create as much heat which eventually rises to the CPU.
- Joined
- Jul 16, 2001
- Location
- Bavaria, GE
Ditto on mine... I have a Swiftech MC462 with the sunon, backed up by the sanyo 120 blowing IN over the top.... it is good that I did this, because myCPU fan died one day while I was at work... the puter was high 40's or 50C when i came home (thats about 120 or so F.... comp was still crunching away at Seti as I promptly crapped myself..... my temps are rock solid and I let the enermax PSU pull all air out of the case (another sanyo 120 in front) pressurizing the case will create more turbulence, and mixing, which will -more- (yes yes tiny %) effectively seperate the warm and cold air... it works, vents on top of my case are warm to the touch, while the bottom vents always have a cool breeze...... just my .02 Jim
flixotide said:
- Joined
- Nov 6, 2002
Re: Re: Re: Side fan airflow question
when you do something like that, you are taking the airflow away from the CPU fan....so instead of flowing across the CPU fan you are taking the air away from the CPU...so instead of a direct line of air flow...you have created a L shape with a small dead spot with little air flow to the CPU fan.......and with the fan blowing directly on the CPU, you are putting the air directly to the CPU...not taking away...and you still have exhaust...rear fan...
And if you think this wont work...that's up to you...but when I added this mod...my CPU temps dropped by over 5c at idle and full load....I idle at system temps and only 5c at full load...doing the way you stated...I idle at 5c over system temps and 13c over at full load...
Now about your edit...in your senerio...you are blowing the hot air from the VC directly up to the CPU to use...this in turn will make the CPU use hot air...unless you have 3 or 4 major CFM fans for exhaust...and in this situation, you still want a top mounted fan blowing directly on the cpu ot get cooler outside air to the CPU so it will not be using the system and VC hot air too cool...
Black_Paladin said:
when you do something like that, you are taking the airflow away from the CPU fan....so instead of flowing across the CPU fan you are taking the air away from the CPU...so instead of a direct line of air flow...you have created a L shape with a small dead spot with little air flow to the CPU fan.......and with the fan blowing directly on the CPU, you are putting the air directly to the CPU...not taking away...and you still have exhaust...rear fan...
And if you think this wont work...that's up to you...but when I added this mod...my CPU temps dropped by over 5c at idle and full load....I idle at system temps and only 5c at full load...doing the way you stated...I idle at 5c over system temps and 13c over at full load...
Now about your edit...in your senerio...you are blowing the hot air from the VC directly up to the CPU to use...this in turn will make the CPU use hot air...unless you have 3 or 4 major CFM fans for exhaust...and in this situation, you still want a top mounted fan blowing directly on the cpu ot get cooler outside air to the CPU so it will not be using the system and VC hot air too cool...
OP
- Joined
- Dec 19, 2000
- Thread Starter
- #12
I didn't buy any new fans, but I decided to do some reconfiguring of the current ones I have.
- switched the window fan (agp level) back to blowing air in.
- moved one of my exhaust fans (sub PSU) to the bottom front of the case and switched it to be an intake
- I left the uppermost ehaust fan (sub PSU) blowing air out of the system.
This leaves me room to get another fan for exhaust, but its working quite well. Cpu & case temp are both down 1-2C due to this.
Thanks for the input
- switched the window fan (agp level) back to blowing air in.
- moved one of my exhaust fans (sub PSU) to the bottom front of the case and switched it to be an intake
- I left the uppermost ehaust fan (sub PSU) blowing air out of the system.
This leaves me room to get another fan for exhaust, but its working quite well. Cpu & case temp are both down 1-2C due to this.
Thanks for the input
I have a side fan right over my HS. When I take it off my IDLE temps are 40°/27°. When I put it back on my temps are 39°/28°. I'm guessing the CPU is cooler b/c cool air is going directly to it. On the other hand I think the system temps go up b/c the side fan is blocking some of the heated air from rising.
You should def. have a fan in the front bottom to draw air into the case and then rear for the exhaust. I'd def. keep the side fan you have blowing in on the VC. Good to see you dropped your temps a little.
You should def. have a fan in the front bottom to draw air into the case and then rear for the exhaust. I'd def. keep the side fan you have blowing in on the VC. Good to see you dropped your temps a little.
Very interesting post Pest and very interesting results.
I have recently bought a new Thermaltake Xaser3 V1000a Black case which comes with 7 case fans all 80mm Two lower Front air intakes one exhaust at the top two rear exhaust and two side panel exhaust. These stupid orange fans that came with the case I replaced with 7 LED Antec fans each operating as such
Fan Speed 2,600 rpm (avg.)
Volumetric Airflow 34 CFM
I have the front two as air intakes the Top one as Exhaust the two in the rear as exhaust and the two on the side exhaust. I also have a Power Supply with an interal lower 60mm air intake fan and 80 rear exhaust fan. This is getting confusing maybe i hope not. I put an 80 mm FAN, Fan Speed 2,600 rpm (avg.)
Volumetric Airflow 34 CFM on top of an MCX462+ Swiftnet Heatsink I think thats the number. I want to know if my fan set up is ok and if the low rpm and 34CFM on my CPU which will be a P4 2.4C all be enough for adequate cooling and maybe room for OCing?
ANother question Ive been pondering in my head is to whether or not have the 80mm fan on top of my heatsink suck air on to the fins or take air away from the fan.
If air is sucked in it gets rid of the air inbetween the fins, if it sucks air out then the fan draws the heat coming off the heatsink into the case. SO mind boggling for me help me out
I have recently bought a new Thermaltake Xaser3 V1000a Black case which comes with 7 case fans all 80mm Two lower Front air intakes one exhaust at the top two rear exhaust and two side panel exhaust. These stupid orange fans that came with the case I replaced with 7 LED Antec fans each operating as such
Fan Speed 2,600 rpm (avg.)
Volumetric Airflow 34 CFM
I have the front two as air intakes the Top one as Exhaust the two in the rear as exhaust and the two on the side exhaust. I also have a Power Supply with an interal lower 60mm air intake fan and 80 rear exhaust fan. This is getting confusing maybe i hope not. I put an 80 mm FAN, Fan Speed 2,600 rpm (avg.)
Volumetric Airflow 34 CFM on top of an MCX462+ Swiftnet Heatsink I think thats the number. I want to know if my fan set up is ok and if the low rpm and 34CFM on my CPU which will be a P4 2.4C all be enough for adequate cooling and maybe room for OCing?
ANother question Ive been pondering in my head is to whether or not have the 80mm fan on top of my heatsink suck air on to the fins or take air away from the fan.
If air is sucked in it gets rid of the air inbetween the fins, if it sucks air out then the fan draws the heat coming off the heatsink into the case. SO mind boggling for me help me out
