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question about cfm's and rpm's on fans...

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nut

Registered
Joined
Oct 24, 2002
what exactly is the difference between 80mm and 92mm fans, other than the size of course.

Say for instance an 80mm fan that pushes 53 cfm's and pushes like 3900 rpm's and 92 mm fan that pushes 57 cfm's at 2700 rpm's. The 92mm has higher cfm's but lower rpm's. Does that mean that the 80mm fan will cool better because it is pushing air at a higher rate with the higher rpm's.

Or rpm's dont matter, and it all comes down to cfm's. The reason i ask is I am debating between the two and don't know which one to get, I want the best cooling of the two.

Hope it doesnt sound confusing, ... I think i confused myself just writing this darn thing.

Any advice would be appreciated. Thx
 

dxiw

Disabled
Joined
Feb 7, 2002
the cfm is how much air it actually moves..cubic feet per minute. The rpm is just the fan blade spinning. The lower the rpm the quieter, the goal is to get low rpm and high cfm. So you can move a lot of air as quietly as possible.
 

Caffinehog

Übercaffinated Member
Joined
Dec 27, 2001
Location
In the lab
In other words, bigger fans are quieter and push as much, if not more, air. Use the biggest fan you can fit.
 
OP
N

nut

Registered
Joined
Oct 24, 2002
Thanks for the help, so do you think i can manage to fit a 92mm fan on a SLK-800 w/o using a fan adapter. It is only rated up to 80mm i think.
 

Tipycol

Member
Joined
Aug 20, 2002
nut said:
Thanks for the help, so do you think i can manage to fit a 92mm fan on a SLK-800 w/o using a fan adapter. It is only rated up to 80mm i think.

Are you planning to use it as a cooler with high cfm's instead of say a Vantec Tornado? If you are, a lot of people have tried this w/ 92 and 120mm fans and found out that temps were not as good as if they had just used a 80mm fan. However, if you are doing this to get a quieter setup, then it will work just fine.
 
OP
N

nut

Registered
Joined
Oct 24, 2002
Well actually i was doing this to get a cooler setup. I currently have the Mechatronics 53.1 cfm fan. I saw that the 92mm Panaflo fan has higher cfm's by only 4 or 5 cfm though. The noise level would just be a bonus , i sure wouldn't mind it being quieter, but cooling is priority here. Hmm now you got me thinking , i might end up just keeping the mechatronics on if some people have found that the 92mm fans don't cool as well.

The Vantec Tornado is way too loud for my tastes.
 

Tipycol

Member
Joined
Aug 20, 2002
nut said:
Well actually i was doing this to get a cooler setup. I currently have the Mechatronics 53.1 cfm fan. I saw that the 92mm Panaflo fan has higher cfm's by only 4 or 5 cfm though. The noise level would just be a bonus , i sure wouldn't mind it being quieter, but cooling is priority here. Hmm now you got me thinking , i might end up just keeping the mechatronics on if some people have found that the 92mm fans don't cool as well.

The Vantec Tornado is way too loud for my tastes.

Well there were a lot of discussions about this on a lot of threads here. Mostly, the problem is that the large dead spot from larger fans is a problem on the heatsink, but depending on how you place your fan, this might be avoided. Another thing that was a problem was using the adaptors. Using a 120mm fan with a cfm of 120, the guy got a raise in temps due to the fact of the back pressure from the exit of the adaptor being smaller than the entrance. Still, you should experiment becuase you are not planning to use those adators and you just might find a way to put a larger fan on a heatsink and see a good improvement.