Which Direction for Case Fans ?

[Mixman]

Ok I just got my Lian Li V1000B Plus. In it are these 120mm fans.

Scenario 1:

ADDA - seated in front of HDD in chamber below - Intake
ADDA - seated at rear of case - Exhaust
Silverstone FM121 - located in blowhole - Intake
Blower fan - located above rear fan - Exhaust

I have my Zalman 9500 blowing directly into the rear ADDA exhaust.

Scenario 2 :

ADDA - lower chamber - Intake
ADDA - at rear of case - Intake (Changed)
Silverstone - located in blowhole - Exhaust (Changed)
Blower fan - Exhaust

I will have the rear ADDA fan blow into my Zalman 9500. I will change the Zalman around and then have it intake the cool air from the intake fan, instead of exhausting into it as in the above scenario.

Which Scenario will give me better cooling and why ?

Also should I change the ADDA fans to something more powerful ? I believe they spin at 1500rpm and put out about 73cfm. In contrast to the Silverstone I bought, which puts out 103CFM.

 

[Reaper]

go with the front intake and the rest exhaust, using the most powerful fan as the intake in the front, so silverstone in front of the HDD's, rest exhaust, and then there is also a defined airflow, from front bottom to rear top.

 

[Darkala]

go with the front intake and the rest exhaust, using the most powerful fan as the intake in the front, so silverstone in front of the HDD's, rest exhaust, and then there is also a defined airflow, from front bottom to rear top.

absolutly correct, also place your most powerful fan second to intake in the upper rear, as the most heated air output will be there

 

[Mixman]

go with the front intake and the rest exhaust, using the most powerful fan as the intake in the front, so silverstone in front of the HDD's, rest exhaust, and then there is also a defined airflow, from front bottom to rear top.

Do realilize that on the V1000's the front intake fan is in a separate chamber, blocked by the hard drives. I am not sure that too much air will ever get t the upper chamber where the motherboard is located. I think the method of me having that as my only intake will severely curtail the amount of cool air entering the case.

 

[c1001]

Mixman: with the PCV-1000 you should use your most powerful fan to exhaust from the rear, and use convection to draw cool air from the front. As the front is perfortated, this should work pretty well, and as you noted the lower intake fan air will not reach the upper chamber. If that doesn't cool your system enough, you can install a fan in the upper chamber: http://www.hardforum.com/showthread.php?t=973719

 

[Mixman]

Mixman: with the PCV-1000 you should use your most powerful fan to exhaust from the rear, and use convection to draw cool air from the front. As the front is perfortated, this should work pretty well, and as you noted the lower intake fan air will not reach the upper chamber. If that doesn't cool your system enough, you can install a fan in the upper chamber: http://www.hardforum.com/showthread.php?t=973719

Thanks for the find. Temporarily, I can use a Sunon I have, just have to put that on a fan controller....it's loud as hell ! Maybe I will get a Panaflo and put there....I think I can fit a 38mm fan.

So, you just think I should leave it like it is except put a more powerful fan in the rear....as an exhaust ?

 

[c1001]

So, you just think I should leave it like it is except put a more powerful fan in the rear....as an exhaust ?

Yes. I am much more of a noise freak, so that is where I'd put the loudest fan.

You can also experiment with the blowhole to see if temps are affected. Technically, I'd recommend using a blowhole to exhaust as the hot air will want to rise anyway. By having it intake, It may disrupt airflow to the rear of the case, push air to the front of the case and disrupt any convection. However, this is just a less than certain opinion as I haven't tried using my blowhole that way. Try it both ways and see what happens.

 

[Mixman]

Thanks. I am not too much of a silence freak, I am not a Delta lover either. I'll try the blowhole as an exhaust and I'll try the rear fan as an intake. I'll see how the temps match up.

 

[Mixman]

Any 38mm fans I should consider for the exhaust ?

 

[GatorFX]

It's been my experience that even though many builders and case modders strongly recommend using the top fan as an exhaust, since hot air rises, this doesn't always provide the best cooling. A balance of pressure/flow needs to be achieved. I have a WaveMaster tower with an 80mm on top, 2 80mm CoolerMasters in front (intakes), an Antec 80mm rear (exhaust) plus the bottom and rear 80mm fans on my Ultra PSU (PSU fans are often overlooked). The air flow direction of the top fan seems to be more user/case-specific and all other fans should be in their normal configuration, or front for intake and rear for exhaust. I've found that by using the top fan as an exhaust, it doesn't always cool as well as using it to bring air into the case. I've surmised that the top fan was trying to pull hot air from my graphics card across my CPU and HS (my 6800 GPU get very hot!) instead of directly out the back, not allowing the CPU/HS to get the cooler air or flow that it needed. I think the top as exhaust also tried pulling away air that would normally be pulled throught the PSU from underneath and out the back, actually reducing the effectiveness of the PSU fans to move air properly out the back and reduced the effectiveness of the rear fan to pull hot air away from the CPU/HS out the rear. With the top fan pulling and the rear fan pulling, they worked against each other trying to move air. Once I'd reversed the top fan to an intake, CPU temps dropped by a few degrees Celsius (@ 3-5C) and the exhaust air from my PSU feels cooler when placing my hand back there. It seems as if the airflow pathway just worked better in this configuration, so the best thing would be trial and error, to see what works best for you.

 

[DudeItsMe]

It's been my experience that even though many builders and case modders strongly recommend using the top fan as an exhaust, since hot air rises, this doesn't always provide the best cooling. A balance of pressure/flow needs to be achieved. I have a WaveMaster tower with an 80mm on top, 2 80mm CoolerMasters in front (intakes), an Antec 80mm rear (exhaust) plus the bottom and rear 80mm fans on my Ultra PSU (PSU fans are often overlooked). The air flow direction of the top fan seems to be more user/case-specific and all other fans should be in their normal configuration, or front for intake and rear for exhaust. I've found that by using the top fan as an exhaust, it doesn't always cool as well as using it to bring air into the case. I've surmised that the top fan was trying to pull hot air from my graphics card across my CPU and HS (my 6800 GPU get very hot!) instead of directly out the back, not allowing the CPU/HS to get the cooler air or flow that it needed. I think the top as exhaust also tried pulling away air that would normally be pulled throught the PSU from underneath and out the back, actually reducing the effectiveness of the PSU fans to move air properly out the back and reduced the effectiveness of the rear fan to pull hot air away from the CPU/HS out the rear. With the top fan pulling and the rear fan pulling, they worked against each other trying to move air. Once I'd reversed the top fan to an intake, CPU temps dropped by a few degrees Celsius (@ 3-5C) and the exhaust air from my PSU feels cooler when placing my hand back there. It seems as if the airflow pathway just worked better in this configuration, so the best thing would be trial and error, to see what works best for you.

Based on what you said, I'd try it without a fan before I'd try it pushing air downwards. I'm sure I could be wrong, but that kind of setup just doesn't seem quite right to me. Of course, you have the results that worked.However... I wonder how it'd do with no fan at all?

 

[GatorFX]

Worth a try but then it would be almost the same as using the top fan as an intake but without the air pressure and air flow a top fan would provide. No, it doesn't make sense to pull air in from the top if you think only about hot air rising BUT if you think in terms of flow and pressure, it actually does make sense. The air outside of the case (ambient room temperature) will always be cooler than the air inside the case, unless your computer is in an unbelievably hot room or sauna. The air at the bottom of the case isn't going to be that much cooler than the air around the top, unless your case is sitting on an icy cold floor or something. Think of it this way... you're standing in a room next to a hot stove to your left, with an exhaust fan in the ceiling to your right. Now, you open a door that's to your left just opposite the hot stove and place an exhaust fan in the doorway. The fan in the doorway is trying to pull the heat of the hot stove outside, the ceiling exhaust is also trying to pull the air out but also right acrossed your body and you're standing right between both exhaust fans, with a hot stove (the CPU/HS) right next to you. Neither fan is doing a good job keeping you cool this way BUT bring cool air inside from outside by pulling it down from the ceiling, acrossed your right side and pusing air to the left as the door fan exhasusts it. You'll never feel the heat of the stove, since now the airflow is pulling the heat away from you instead of right towards you. See what I mean? Unless the outside air is hotter than the stove (CPU) the movement of air being pulled across and away from the heat source will do the job of cooling! Now does it make sense? I was a bit confused at first too but you can't argue with the results, e.g. lowered CPU temps.. Experiment and see what works best for you. This just works best for me since my graphics card is a second heat source and I don't want hot air being pulled away from it and across the processor, I want the hot air pulled away from it and out the back door, so to speak. With my top fan pulling, it pulls air right over my CPU instead of straight out the back of my case. It cools better pulling air from the top, across my CPU and out the back. Trust me. I know it all sounds weird but the physics are there, regardless of the physics of hot air rising. Every aspect of the flow and pressure must be considered, to achieve the best cooling. You'll figure it out.