Double your fans on the rad equals more cfms?

[davidm71]

I was wondering when you place a fan on the top and bottom of a rad in push/pull is the cfms leaving the case cumalative?

Thanks.

[Church]

Push-pull on rads with double fans (row from each side) will enhance airflow and cooling. But not two times of course .. so, maybe about 1/3 more. Though even that imho is worth it, as for most internal builds ammount/size of rads you can fit in usually is very limited, so every bit helps, especially if it's as simply achievable as just adding another row of fans.

[TilaTech]

Push-pull on rads with double fans (row from each side) will enhance airflow and cooling. But not two times of course .. so, maybe about 1/3 more. Though even that imho is worth it, as for most internal builds ammount/size of rads you can fit in usually is very limited, so every bit helps, especially if it's as simply achievable as just adding another row of fans.

Also, it helps increase the static pressure which is a major plus for radiator cooling.

-TilaTech
Attila S.

[davidm71]

My problem is that I'm in like a negative pressure situation. I've counted all the cfm's going in and out, and I have more air being pushed out by fans than going in. I have my 360 rad with push/pull mounted on the top inside blowing air out. Should have installed them the other way around. Too late to fix as it would be major pain to remove the rad and change fans. So I'm trying to force more air into the case to balance them all out. Good to know that the total leaving the rad isn't the total of both fans. At best I could do a door mod and install another fan to blow air into the case over the cpu socket area so the rad will have fresh air. I've heard of gpu door fans but I wonder if anyone has ever put some fans on their door for radiator cooling...

Thanks.

[Utnorris]

Post a picture and we can probably help a bit more.

[Martinm210]

Here is an old test I did with 38mm fans on an XSPC RS120

http://www.martin.skinneelabs.com/img/FanShroudTest3-38mm2000.png
Push gave my 9.2C delta, where push/pull gave me 7.6C which is about a 17% improvement.

This would probably be higher with more dense type radiators though. Each fan and each rad is also different, but this at least gives you thermal results for one test case to think about.

[BeepBeep2]

Couldn't you compare it to adding a pump in a loop? Flow doesnt really go up much but pressure does?

[davidm71]

Post a picture and we can probably help a bit more.

http://i228.photobucket.com/albums/ee28/davidm671/DSC00577-1.jpg

Every arrow represents a fan. There is also a low rpm 120mm fan on the backside of the motherboard tray that is not shown exhausting air. Also on top of the rad are three standard 50cfm case fans by silverstone. On the underside of the rad are Enermax Magmas 69 cfm 19db fans. Those fans are false advertised as 120mm when they are like 121mm and trying to get them to line up side by side was a pain.

Hard time getting the screws to mate properly. Kind of worried if any of the top fans ever die I'll have to leave them as it would be a pain to swap new. In the front of the case there are two Antec 3 speed 79cfm/30db fans top and bottom with a 140mm 50cfm Thermaltake case fan cooling the harddrives in the middle. There is also an 80cfm 220mm fan on the case door over the gpu area.

Two Magma fans on the rear of the case and a Delta 80mm 50cfm I just squeezed in front of the PSU on the bottom. Its actually the same exact fan that is used in the PC Power Cooling PSU. So there is a lot of air flow going through the case. My northbridge and VRM temps are between 40-50 degrees C. Today my cpu load stock temps for a 920 D0 were around 48-52 degrees during a quick 5 minute prime.

So there you have it. Made a rookie mistake installing those radiator fans. Wish I could go back in time and fix it but can't cry over spilled milk....

Thanks.

[Martinm210]

Couldn't you compare it to adding a pump in a loop? Flow doesnt really go up much but pressure does?

Sure, same thing..just a few more oddities with radiators like shroud depth and the radiator thickness/density that plays into the result.

[Hondacity]

pretty good question....

try this http://www.xtremesystems.org/forums/showpost.php?p=3400300&postcount=1

[Church]

davidm71: why don't you reverse fans on back of case airflow to blow in case to better even out air pressure in case? Them blowing out is usually mostly for air cpu coolers imho.

[davidm71]

davidm71: why don't you reverse fans on back of case airflow to blow in case to better even out air pressure in case? Them blowing out is usually mostly for air cpu coolers imho.

I tried that but it just back flowed rising gpu exhaust because my system lives in a home entertainment decorative type case and the air in there warms up after a while behind the computer. I was thinking of replacing the front fans with some 38mm panaflows or there was another brand that was famous for high high cfms and low noise. Cant remember name...

[Church]

Hmm, if you have three 5.25 bays free, you can put in something like Kama Bay Plus (just replace stock thin fan that almost doesn't blow at all with some good 120mm fan eg. scythe gentle typhoon). Imho it's also possible to dremel out and put fan on bottom of case (somewhere where pump is placed). Another option regarding those two fans in back of case blowing out .. if not reverse, then at least remove them, and close their cutouts with something for dust to not get in. Another option is to cardinally change airflow in case, eg. change fan direction on rad to suck in air from top/outside of case.
Maybe some of these options can help you evening out or even making air pressure in case positive.

[davidm71]

Hmm, if you have three 5.25 bays free, you can put in something like Kama Bay Plus (just replace stock thin fan that almost doesn't blow at all with some good 120mm fan eg. scythe gentle typhoon). Imho it's also possible to dremel out and put fan on bottom of case (somewhere where pump is placed). Another option regarding those two fans in back of case blowing out .. if not reverse, then at least remove them, and close their cutouts with something for dust to not get in. Another option is to cardinally change airflow in case, eg. change fan direction on rad to suck in air from top/outside of case.
Maybe some of these options can help you evening out or even making air pressure in case positive.

I kind of am using my 5.25 drive bays two house two additional 120mm fans one on bottom and one at top that I custom mounted with aluminum self made frame to hold in place. I hear the San Ace fans are good and may use them in the future. Yesterday I put a high powered 80mm fan at the bottom of the case between the psu and and water pump. No room for a 120mm thanks to an extra long psu.

Funny story a couple years ago had a pc power cooling psu that was acting up and pc power sent me a replacement fan. Like wtf pc power cooling am I suppose to do with an extra psu fan. Well I finally put it to use. A bit noisy of fan.

Thanks.

[Vetalar]

maybe reversing magmas and add some "cardboard screen" to split hot air from intake fans... or put Your GPUs under water - no exhaust, no hot air...

[Church]

San Ace fans are good .. among similar fans of high performancy AND high noise.

[davidm71]

I was thinking of installing like a fan directly over the gpus with a shroud over them to blow out the gpu heat out the back of the case. Was thinking about this:

http://www.performance-pcs.com/catalog/index.php?main_page=product_info&cPath=130_210_750_758&products_id=22329

[davidm71]

Thanks guys for recommending the 'Kama Bay' mounting kit. I just ordered a couple of them along with a couple San Ace 100 CFM 39db 38mm fans to replace these old Antec 70 CFM fans I had in there. Not only that its going to look way more professional with the Scythe Kama Bay in there compared to my piss poor job of these homemade aluminum frames that were holding the antecs in place. These San Aces should provide an additional 60 cfm. This is what I ordered:

http://www.scythe-usa.com/product/acc/073/images/sckb2000-fro_400.jpg

Thanks.

[Church]

I'd rather put some scythe GT fan in it instead of loud san aces.

[davidm71]

I did by a fan controller also to keep the fan noise in check. So like on those warm days I'll max it out and lower the rpms on the cooler days....

[elk0019]

just one question sort of related as to not open another thread:

have a rx240 rad in push pull and i'm undecided wether to put them on shrouds as i've heard it does have some kind of shroud integrated but i would like to know if proper shrouds wil benefit better..

[Church]

Shrouds will help a little bit. If you have enough space, you can hack up some old fans to get cheap shrouds. For me rad with push-pull fans already is fat enough package, and i somehow a bit dislike looks of rads+shrouds+fans.