Fan layout query

Gimpymoo · 18 Jul 2019 at 18:57

Hi.

Am running a Fractal R5 as a file server, 8 HDDs, so is getting rather toasty with the default:

1 x Fractal 140MM Gp14 at the Front (Pull IN)
1 x Fractal 140MM Gp14 at the rear (Push out)

Although a great case, cooling is not their forté but they do hold 8 HDD's so making the best of it

.
I need to add more fans.

I am going to add another to the front so 2 x GP14 140mm at the front (maximum).

If I add 2 or at the top pulling out (not filtered so would prefer to avoid dust intake), would that affect the cooling mojo if I had:

2 x 140MM FRONT (Side intake)
2 x 140MM TOP (Pushing out)
1 x 140MM REAR (Pushing out)

My thinking is the HDD's are getting that hot that the front fans are having little effect on system temps as by the time the air gets to the system having passed the HDD's, it is already too warm.

Thanks.

Meddling-Monk · 18 Jul 2019 at 19:12

Think it'll somewhat depend on what speeds you're running those fans at as well. If you lower the three exhaust (Pushing Out) fans to around 80-90% (assuming Intake: Pull In fans at 100%) then you should keep Positive Pressure whilst keeping the cooling as you are aiming for.

You might want to find out what those fans push/pull in terms of air and then work out how much will be coming in, and how much going out when run at specific speeds to really make the most of it. Although I will note that Positive Pressure doesn't mean no dust, just less compartively. So it may be that some Negative Pressure might not be so bad. Depends on situation of course.

Gimpymoo · 18 Jul 2019 at 19:46

Thanks for the info.

The fans are 1000rpm with 68.4 CFM airflow.

0.71mm H2O pressure.

https://www.fractal-design.com/home/product/casefans/dynamic-series/dynamic-gp-14

Meddling-Monk · 18 Jul 2019 at 19:56

Well, assuming the Intakes are at 100% (reduce as necessary), then I'd have the Exhaust fans at:

Intake: 2x 68.4 = ~136.8CFM
Exhaust: 3x 68.4 = ~205.2CFM

So if we have the Exhaust at 70% of their maximum speeds, we have ~143.64CFM. Which is still more than the Intake at 100%, but close enough. But it'll be Negative Pressure.
At 60% we have ~123.12CFM, so will maintain Positive Pressure.
And at 65% we have 133.38CFM, and will have Positive Pressure (just about), but requires you being able to control fans to single digit percentages, which may not be common depending on motherboard/controller, etc.

All the while probably doubling or near doubling your airflow for cooling. So I'd probably aim for 60% of maximum fan speeds for the Exhaust whilst you keep your Intakes at 100%. Reduce as necessary if the Intakes are too loud for you though.