Archived Posts » 59,699,509
One 170mm fan or four 80mm fans?
4/29/2012 2:58:28 AM
If I add identical fans, can I double CFM? IE, one 40CFM fan moves 40, two 40CFM fans move 80, four 40s move 160CFM, etc.... I understand there will be many variables in this equation, but I am looking for a baseline. Trying to decide if a 170mm fan that claims 150CFM would be better than, say, four 80s that move 50/ea.
Even if I could get the same CFM out of either setup, which is likely to have the lesser amount of noise?
Even if I could get the same CFM out of either setup, which is likely to have the lesser amount of noise?
4/29/2012 3:13:13 AM
The larger fan will generate significantly less noise. The smaller fans will have the advantage of higher static pressure. I'm not sure about the flow scaling with additional fans, but it is related to the static pressure and how much resistance to air flow you have.
4/29/2012 4:10:55 AM
Thanks. I'm experimenting with a positive pressure setup in a somewhat tightly packed micro ATX tower. Noise is a concern... But I'm wondering if I need more airflow or higher static pressure?
Presently have three 120mm fans bringing air in from the front (two are push/pull though a Corsair H60). One 120mm fan is blowing air out the top, and the PS fan (140mm) is doing the same. Noise is there but not a huge deal. although I am about to add a GTX295 to the setup.
I am fabricating a gasket-sealed MDF side panel to experiment with a single 200mm fan in either push or pull (with no other fans except the power supply), or a 170mm, or a few 120mms, or a few 80mms.... etc. I'd like positive pressure because I can filter the incoming air easily. If temps are lower with the large side fan(s) pulling air out instead, it will take some effort to seal up the case to direct airflow where I need it, and to filter it.
Before I dump $100 on fans and build a half dozen different side panels, I'm trying to get a basic education on how this would work. I can tolerate some noise, but this is a bedroom PC so it can't sound like a wind tunnel when the lady of the house is trying to sleep and I'm on ARF
There will be a fan controller (I'm using one now) but honestly, after tinkering with this system like we do our AR15s, I'm embracing the KISS concept (ala 20" A2) and a single large side fan working in a positive pressure setup would be my absolute goal, if practical.
Presently have three 120mm fans bringing air in from the front (two are push/pull though a Corsair H60). One 120mm fan is blowing air out the top, and the PS fan (140mm) is doing the same. Noise is there but not a huge deal. although I am about to add a GTX295 to the setup.
I am fabricating a gasket-sealed MDF side panel to experiment with a single 200mm fan in either push or pull (with no other fans except the power supply), or a 170mm, or a few 120mms, or a few 80mms.... etc. I'd like positive pressure because I can filter the incoming air easily. If temps are lower with the large side fan(s) pulling air out instead, it will take some effort to seal up the case to direct airflow where I need it, and to filter it.
Before I dump $100 on fans and build a half dozen different side panels, I'm trying to get a basic education on how this would work. I can tolerate some noise, but this is a bedroom PC so it can't sound like a wind tunnel when the lady of the house is trying to sleep and I'm on ARF
There will be a fan controller (I'm using one now) but honestly, after tinkering with this system like we do our AR15s, I'm embracing the KISS concept (ala 20" A2) and a single large side fan working in a positive pressure setup would be my absolute goal, if practical.
4/29/2012 6:07:27 AM
since we known absolutely nothing about your system i am going to suggest one big case fan(blowing air out the back of the case) set to speed up with high cpu usage
4/29/2012 2:21:01 PM
Originally Posted By cruze5:
since we known absolutely nothing about your system i am going to suggest one big case fan(blowing air out the back of the case) set to speed up with high cpu usage
since we known absolutely nothing about your system i am going to suggest one big case fan(blowing air out the back of the case) set to speed up with high cpu usage
No rear evac fan in this case (Silverstone Sugo SG04 –– http://www.silverstonetek.com/product.php?pid=235&area=en)
Phenom II X4 @ 4GHz, Corsair H60. GTX295 will be coming in a couple of weeks. I'm in the process of getting baseline numbers for temps at idle and under load using the current cooling setup, and will then use two different side baffles to test 4x120mm fans at low/med/high speeds, and one 200mm fan at the same. Will do positive and negative case pressure and report back if there's interest. Goals will be cooling, noise, and lack of dust, in that order.
Incidentally, if anyone has any advice on filter material, I'm all ears. Have heard of some guys using pantyhose material; I was planning on fine screen mesh (house window screen) to start. Hoping to minimize air turbulence but maximize airflow, given the material.
5/1/2012 4:11:11 PM
So your thinking of having a positive static pressure- So you will have more airflow going into the case then what is being exhausted. Depending on the case and setup, etc this may create hot spots. if to much. I would go with 1 big quite adjustable fan, and either on the top or top rear of the case the biggest quietest fan you can install. back when I used overclock and build my own case's I would try have the same amount or just a bit more for the intake then exhaust due to also having the psu exhaust fan, gpu fans that also exhaust through the back. That and thermal probes on the cpu heatsink, gpu's, northbridge hs, probe for intake air temp and exhaust and general case temp. I had a 8 zone controller that was dang nice you can setup with temp limits for fans to turn on and off.
