which way should i have fans going?

[kc2gub]

ok, i have my 1 rear fan pointing out <---- like this and 2 front fans putting into the case, again like this <----, ive had these like this for a while and believe this is right, but today i modded my case and installed a top case fan..this is whats confusing me...i put the fan blowing down into the case and it lowers cpu temps literally instantly and lowers the cpu temp by like 5 degrees! but..it raises case temps by like 5 degrees....which is weird to me because if the case is warmer, the cpu is in a warmer place therefore it to should be warmer, but its not it drops 5 degrees while case rises 5..then i reverse the top case fan and make the fan blowing out therefore i think pulling the hot air out of the case and out..this is how its supposed to be...i believe, but temp wise it seems to do nothing at all, like the fan wasn't even there...so should i keep it blowing down which lowers cpu temps 5 degrees, but raises case like 4 or 5 degrees? i would think the cpu is more important than the case temp and also, by pointing it down , if its lowering the cpu that much it must also be lowering ram and video card temps as well which is good...so what do you guys think?

 

[KouklatheCat]

That is wierd, what are you using to measure the temps?

I am guessing that when the fan is blowing down into the case it might be forcing air into the HSF and pushing the hot air that sits around the center of the fan on the heatsink out (hope that makes sense). Since its pushing the hot air out of the center of the heatsink that would explain the drop in CPU temps and the rise in case temps.

Just a guess, hope it helps.

 

[Jeriko]

Originally posted by: kc2gub
i put the fan blowing down into the case and it lowers cpu temps literally instantly and lowers the cpu temp by like 5 degrees! but..it raises case temps by like 5 degrees....

I don't have a suggestion - as I'm in the same boat as you wondering about how the top fan "should" be mounted - but if your power supply has a forward exhaust it may be blowing warmer air directly into the path of the top intake. I haven't powered up my new power supply yet, and it's the first one I've had with front and rear fans (and two bottom fans ), but I think the top holes are to exhaust the front exhaust of higher-end PSUs.

-J

 

[kc2gub]

ya i understand what your saying...i guess ill leave it the way where the cpu temps are lower...because im sure since its loweing cpu so much its also lowering ram etc, but then the case temps show as being higher..which is weird...im using bios to read and motherboard monitor which shows same temps as bios..very weird..cpu drops greatly, case temp rises though..maybe ill put other way and let it go overnight and see what happens, maybe it takes a while to suck all that hot air out..

 

[Jeriko]

^ Could it be that your case temperature probe is in the path of the warm air blowing down from the HSF, giving you an artificially high reading?

-J

 

[PliotronX]

Taking into consideration that heat rises, having the top fan as an intake is creating an airflow short circuit somewhere that is obviously close to the probe for the system temp. I would say if your CPU doesn't overclock any better with the top fan as an intake than without a top fan at all, I would keep the top fan as exhaust because the airflow is better whether the system temp probe reports it or not.

 

[Jeriko]

I hadn't thought of heat rising problem. Glad you mentioned it.

Only problem then is, in my set up, I'm going to have three instakes somewhat obstructed by filters and the front of the case (which has air holes - but it will still cut down on airflow), and three relatively unhindered exhausts. Won't this cause an imbalance?

Fortunately, I have a Vantex Nexus fanbus, and I can cut down the speed of the rear and top exhaust fans if I need to.

-J

 

[kc2gub]

well, i decided to leave it as an exhaust, air blowing out...because i left it like this overnight and gave it a chance to do its job and the temps went down a lot and stayed down after gaming..heat rises, so having it as an exhaust should suck the hot air that rises to the top..by the way my case is 26 and cpu is 42 which is very cool considering im using the stock amd heatsink!