enough airflow?

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vveeger
Posts: 5
Joined: Sun Dec 08, 2013 9:27 am

enough airflow?

Post by vveeger » Sun Dec 08, 2013 1:25 pm

building a large server/desktop

relevant hardware:
Case: Lian-Li PC-A79
Disks: 8x WD-SE 4Tb in raid (hot swappable)
Processor: i7 4770k
CPU-cooler: Corsair H110i (closed loop water)
Graphics: not yet known but fast

Inflowing fans: 3x120mm in front of the 8 drives (airflow obstructed a bit by HD's and backplane)
2x120mm in left side panel
Outflowing fans: 1x120mm top rear
2x120mm top (below Corsair's radiator)

Although I realize that this won't be a super quiet system, I'm wondering what airflow is needed.
Thinking about NB-Multiframe S-series:
8x120mm M12-1 - 750rpm - 8dba - 58.0 m3 or
8x120mm M12-2 - 1250rpm - 16dba - 87.0 m3

Would the M12-1 series be enough or should I opt for the M12-2 series?

bonestonne
Posts: 1839
Joined: Mon Feb 05, 2007 2:10 pm
Location: Northern New Jersey
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Re: enough airflow?

Post by bonestonne » Sun Dec 08, 2013 10:19 pm

That's too much....

I would lose the intake fans and side panel fans completely. Run exhaust fans on rear/top only. Let air pressure work it's magic.

More fans does not always equal better cooling. For a properly silent PC, fewer fans in thought out positions will work more magic than many fans where ever they can bolt onto the case.

Consistent air movement is crucial. I would go for the 1250RPM fans, because if they're good fans (and NoiseBlocker fans are), then they'll still be pretty reasonably quiet. Even more so if they're PWM controlled, because they'll slow down when temps are lower (and in a system like this, I see no reason for why the temps would shoot up).

vveeger
Posts: 5
Joined: Sun Dec 08, 2013 9:27 am

Re: enough airflow?

Post by vveeger » Mon Dec 09, 2013 7:14 am

bonestonne wrote:That's too much....

I would lose the intake fans and side panel fans completely. Run exhaust fans on rear/top only. Let air pressure work it's magic.

More fans does not always equal better cooling. For a properly silent PC, fewer fans in thought out positions will work more magic than many fans where ever they can bolt onto the case.

Consistent air movement is crucial. I would go for the 1250RPM fans, because if they're good fans (and NoiseBlocker fans are), then they'll still be pretty reasonably quiet. Even more so if they're PWM controlled, because they'll slow down when temps are lower (and in a system like this, I see no reason for why the temps would shoot up).
Thanks a lot for your input bonestonne,
when only pulling air out of the system (rear top 1 fan, top 2 fans), I think the air will come in there where it is most easiest to flow which in this case would be the 2 side panel howls because the front intakes are obstructed a bit by the 8 drives and the backplanes behind the drives. This could cause no cooling at all for the drives which operate 24/7.
Would you argue to close the side panel wholes and other minor wholes and so forcing the inflow of fresh air over the drives?

a picture of the case (seem not be able to attach one) can be found at:
http://www.lian-li.com/en/dt_portfolio/pc-a79/

edh
Posts: 1621
Joined: Mon Mar 17, 2008 1:49 pm
Location: UK

Re: enough airflow?

Post by edh » Mon Dec 09, 2013 7:58 am

With 8 drives in a mounting system with only minimal dampening and an aluminium case, I think the baseline noise will be high enough that fan configuration is not going to be the biggest issue for noise. Are you absolutely set on that case?

Perhaps it is better to understand what it is you intend you use the computer for? Is it likely to be running highly parallelised, CPU intensive calculations for hour after hour or only occasional times when it will be running hot?

vveeger
Posts: 5
Joined: Sun Dec 08, 2013 9:27 am

Re: enough airflow?

Post by vveeger » Mon Dec 09, 2013 8:42 am

edh wrote:With 8 drives in a mounting system with only minimal dampening and an aluminium case, I think the baseline noise will be high enough that fan configuration is not going to be the biggest issue for noise. Are you absolutely set on that case?

Perhaps it is better to understand what it is you intend you use the computer for? Is it likely to be running highly parallelised, CPU intensive calculations for hour after hour or only occasional times when it will be running hot?
Yes edh, I realize it will be hard on the noise issue, but need a case with 8-9 hot-swappable drives.
Need enterprise quality on the drives which also doesn't help.
I can't find any alternative utilizing that.
It's a combination of a normal desktop usage, occasional gaming and a server, most of the time it will be idle.
Planning to damp the case and bays with bitumen plates

edh
Posts: 1621
Joined: Mon Mar 17, 2008 1:49 pm
Location: UK

Re: enough airflow?

Post by edh » Mon Dec 09, 2013 10:40 am

When you talk about server use, what is it serving? If it is only being used as a fileserver, how many clients are going to be connecting to it, for what applications and how much of the time does it need to be running for? If when you are talking about a server you only mean a fileserver then you'd be better off splitting these tasks and having a NAS with all of the disks in somewhere out of the way where the noise is less of an issue. Then you can have a far quieter desktop computer which you switch on as and when you want it.

bonestonne
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Re: enough airflow?

Post by bonestonne » Mon Dec 09, 2013 11:12 am

I would completely argue to close the side panels, and also some of the front 5.25" bays I would block off in order to force the air to come in where the drives are. This airflow will keep the drives plenty cool. They do not in fact need lots of airflow, a little goes a long way. Hard Drives do not get very hot (in most cases).

I run my computers almost exclusively on positive air pressure because I find it to cool better, and I also recently upgraded to an SSD, and when I opened my case (about 8 months of not being touched) and there was no noticeable buildup of dust anywhere in the case. My house is cleaned on a daily basis, so that helps, but that wouldn't prevent dust. Direct your airflow very deliberately by providing a specific intake area, and a specific exhaust area. I don't remember exactly where they are, but somewhere there are intel spec sheets that (up until pretty recently) still were pretty specific about front to back airflow in this manner. Unfortunately, it never really gets into whether a side intake or other vents around the case affect the airflow in a negative way or not.

Now that CPUs are running very cool again (thinking back to before heatsinks were even used), it's almost irrelevant outside of now the NUC machines coming out. Fanless isn't quite here just yet again.

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