Case fan positioning

[DinoDeno]

I have the corsair 400C Black case it comes with 2 fans 1 140mm at the front and 1 120mm at the back im planning to use the corsair h115 AIO cooler and i think i will place it at the front and take the 140mm fan and place it on the top do you think this is a good idea to do ? do i need to buy any other fans ? if i do which ones do you recommend thank you

 

[Karsten75]

To keep the maximum dust out of your case, it makes sense to have "positive airflow" where more/larger fans push more air into the case through filtered inlets than there are fans pushing air out. Usually the idea also is for cool air to enter at the front/bottom and warm air to be vented out the rear/top.

Some radiators can only fit in the front inlets and then it's OK to have the slightly warmer air blow over the components.

 

[DinoDeno]

So is the thing i thought the h115 cpu cooler setup at the front with the radiator facing inside and the fans outside which pushes air through the radiator and then in to the case ... and the 140mm on the top with the 120mm at the back what do you think?

 

[Karsten75]

fans outside the case is a very, very bad idea. You can probably mount the rad inside and mount the fans so that they still pull air through the radiator.

 

[JackNaylorPE]

Note that the h115 is not listed on Corsair's site a sbeing compatyible with this case so better check what fits

http://www.corsair.com/en-us/carbide-series-clear-400c-compact-mid-tower-case

Compatible Corsair Liquid Coolers = H55, H60, H75, H80i, H90, H100i, H105, H110

The H115 is running at $140 and for that you get a weak pump, aluminum rad, mixed metals (galvanic corrosion issue) and no way to augment the corrosion inhibitors which slow that corrosion. For $150, you can get a set of custom water loop, pre-assembled at the factory which outperforms anything Corsair has to offer and is much quieter. Again, check what fits

http://www.swiftech.com/h240x2.aspx

Your case allows for:

120mm Fans
Top: 2 x 120/140mm
Rear: 1 x 120mm (Included)

140mm Fans
Front: 3 x 120mm or 2 x 140mm (1 x 140mm included)

First Id mention that the Swiftech 320 V2 is an option which would give you 3 x 120mm blowing in (check clearances) for even more performance

With the H240 (2 x 140mm) in front, as intakes... 140 in the top as exhaust sand 120 in rear as exhaust, you will likely find yourself in an negative pressure situation. here dust is the minor concern as what is carrying that dust in is the much of the hot air exhaust from your GFX card and your PSU.

I would but the H240 on top with rad fans, as always, blowing in. here's a quick guestimate as to what will happen. Using the 120mm exhaust fan (no filter) as a unit of "1 fan equivalent"

140mm fans produce about 1/3 more air but the y are restricted by filters or rads, we can lose up to 1/3 ... so those fans get the "1 fan equivalent" designation too.

So you have the equivalent of 3 120mm fans in and 1 blowing out, resulting in a positive case pressure situation which means:

a) Without negative pressure, the case will not suck in air thru the rear case grilles and slot covers and since that air source includes a bunch of PSU and GFX card exhaust.

b) When folks talk about intake air thru rads, the air temp increase from the 90 watt CPU is the stated concern, but the temp increase from the 650 watt PSU and the 250 watt GFX card coming in thru the rear grilles somehow escapes notice. The latter is the bigger concern.

c) Of course when that hot air is sucked in thru the rear grilles, it brings dust along with it.

d) I have 4 water blocks in our test rig pulling off over 700 watts of heat ... thru two radiators served by intake fans. Running Furmark, there is no temperature increase, of MoBo, SSDs, SSHHs or anything else other than the expected increase in CPU / GPU temps from the stress test loadings ... and even if there were .... what impact would 2C warmer air have on any of the components ? The air inside your case will turn over at least once a second which fresh ambient air fills the case 1 to 2 times every second.

Your case = 16.73" x 8.46" x 18.27" = 1.5 cu.ft... the air volume we can estimate at 80% of that or 1.2 CF

I'll assume that they are Corsair 1650 fans which have a reported air flow of 57.24 CFM ... let's say they actually deliver 40 ... 4 fans x 40 cfm = 160 cfm... that's 2.67 cf or air per second.... the entire case volume is removed and replaced more than 2 times per second with fresh cool ambient air. With that level of air flow available you have no concern about radiator exhaust heating up anything.

 

[JackNaylorPE]

So is the thing i thought the h115 cpu cooler setup at the front with the radiator facing inside and the fans outside which pushes air through the radiator and then in to the case ... and the 140mm on the top with the 120mm at the back what do you think?

There are two options:

Fans in "Pull"
Fan | Radiator | Case Wall | <== air flow

Fans in "Push
Radiator | Fan | Case Wall | <== air flow

based upon testing over at Marttins Liquid Lab, It was determined that it likely won't make much difference. In his tests, as i recall

Push was more efficient at fan rpms from 300 - 1650 rpm
Pull was more efficient at fan rpms from 1850 and up

It was pretty much a wash from 1650 - 1850 or so and that's where i expect your fans will spend most of the time when being stressed. At lower rpms, push has the advantage and this is where things will sit whenever you are not stressing the CPU ... aka 'most of the time"... So id put the fans in push (inside the case).

 

[DinoDeno]

What about the corsair 100i v2? Jack said that the h115 is not compatible and recommended me custom water cooling but you see what i have to buy all the stuff from amazon and i am going to be using this pc for a long time should i go for the h100i v2 or do you recommend anything else?