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Optimum fan layout for Fractal Design Define R3?

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June 26, 2012 3:13:16 PM

Hello, been a lurker for a long while, but this is my first post.

I have recently upgraded my home PC (specs in my sig) and will be looking to OC, so good airflow is quite important. I have the excellent Fractal Design Define R3 case and have purchased lots of fans to maximise airflow.

I have an NZXT Sentry Mesh fan controller fitted, which has five sliders on to control fan speed, along with some fan splitters to allow me to run multiple fans on one controller, if needed.

My current setup (negative pressure) is:

*Front [INTAKE]: 2x Zalman ZM-F3 120mm fans (@12v and shared on one controller)
*Bottom [INTAKE]: 1x FD Silent 140mm fan (set to low)
*Top [EXHAUST]: 2x FD Silent 140mm fans (front set on low, rear higher)
*Rear [EXHAUST]: 1x Xilence RedWing 120mm fan (set on high-ish setting)
*CPU: CoolerMaster Hyper 212 EVO (PWM-controlled 120mm fan blowing straight out the rear - PWM set to 0.75 in BIOS)

I haven't mounted a side fan (space for a 120/140mm), because the graphics card with the Twin Turbo mounted is so wide that a fan would be pressed up against it.

So my questions are three-fold:

1) Should I change my rear fan to one using the PWM header on the mobo to sync with the CPU cooler?
2) Would it be better to ditch the bottom fan and so have 2x intake vs 3x exhaust?
3) Have I gone overboard with the number of fans in my case?!?
June 26, 2012 3:17:46 PM

Hmm, my sig hasn't appeared for some reason and I can't edit that first post. Sorry about that!
June 26, 2012 6:30:33 PM

1: Is your cpu cooler pushing out the rear or the top? Optional really.

2: Keep bottom intake, making it exhaust would pull more fresh air from the front thru the bottom than hot from the inside.

3: No.
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June 26, 2012 7:19:36 PM

You could never go overboard on fans :lol: 

It would help a lot (well, helps me) if I have an image to work with. That way we can understand the setup a bit better.
June 26, 2012 8:18:16 PM

iendigma said:
1: Is your cpu cooler pushing out the rear or the top? Optional really.

2: Keep bottom intake, making it exhaust would pull more fresh air from the front thru the bottom than hot from the inside.

3: No.


Thanks for the reply. 1: Pushing out the rear. 2: I actually meant should I not use a fan in the bottom? I read somewhere that if you have more than 4 fans (2 push, 2 pull), a bottom one thrown in the mix could actually disrupt the flow of air. I have no intention of putting exhaust on the bottom - I know that hot air rises.

eddieroolz said:
It would help a lot (well, helps me) if I have an image to work with. That way we can understand the setup a bit better.


Right you are!



Blue arrows are intake, red arrows are exhaust. Yellow arrows are moving warmed air inside the case (VGA fans & CPU fans). Stock cooler will be replaced with the Hyper 212 EVO tomorrow, which again will be pointing directly at the rear exhaust. Also replaced the Xilence with a Zalman in the rear for the moment - tinkering!
June 26, 2012 8:46:00 PM

Thanks for the image!

To me, the current layout looks good. You've got airflow inside the case that travels in one direction in a Z shape.

Time to see if other case air flow experts see anything wrong with this.
June 26, 2012 9:44:09 PM

eddieroolz said:
Thanks for the image!

To me, the current layout looks good. You've got airflow inside the case that travels in one direction in a Z shape.

Time to see if other case air flow experts see anything wrong with this.


Thanks, eddieroolz. What do you think about the rear fan - that's my big area of uncertainty.

The rear fan in the photo (the Zalman) is currently being run off the fan controller. If my CPU starts getting hot (gaming, Lightroom, Blender, etc), I think I'd prefer the rear fan to be on PWM, so that it would ramp up in speed when the CPU cooler does, thus preventing hot air from being trapped around the CPU...

Thoughts?
June 27, 2012 1:23:04 PM

I'd just run it at constant speed myself, but looks like yours are PWN-controlled, so there's no harm in syncing it to your CPU temperature.

If you're really concerned about air stagnating between the cooler and the case fan, you could always invest in a higher-CFM PWM-controlled fan. That way you remove any possibility that the case fan will be the limiting factor.
June 27, 2012 1:54:37 PM

eddieroolz said:
I'd just run it at constant speed myself, but looks like yours are PWN-controlled, so there's no harm in syncing it to your CPU temperature.

If you're really concerned about air stagnating between the cooler and the case fan, you could always invest in a higher-CFM PWM-controlled fan. That way you remove any possibility that the case fan will be the limiting factor.


Again, thanks for the reply eddieroolz. I actually have both a 3-pin fan (currently hooked up to my fan controller giving constant speed) as well as a 4-pin PWM fan (which I am not currently using in this build).

That is the crux of my question - 3-pin rear fan and control it via the fan controller, or PWM rear fan synced with the CPU cooler?

Was kind of interested in what other people do in builds using a similar fan setup.

Sorry for being obtuse!!
June 27, 2012 2:07:49 PM

No problem. Thanks for clarifying.

The way I see it, fan controllers are nice but if you could leave the job up to the algorithm, why not? It eliminates one more thing you need to worry about, and allows you to get onto whatever you want to do.

My back fan slot is currently occupied by a Corsair H80, but if I had it free I would definitely plug it into PWM. In fact, I wish the Gentle Typhoons that I use right now would support PWM.

You could also see if anyone else has anything to say as well.
June 27, 2012 2:10:39 PM

Can't you remove some of those 5.25" bays you aren't using? Sure as heck wouldn't hurt airflow.
!