[Beowulf] AMD Roadrunner open compute motherboard

[Lux, Jim (337C)]

What's interesting is how much power the fan consumes.. 

Sunon SG4028 is a 40x40mm fan 28 mm long (single fan).  The 16.8 CFM flavor spins at 13krpm and consumes 2.6 watts.

The PF4056 which is a stack of two fans 40x0mm, at 15-18krpm consumes almost 11W to push 27 CFM ( at zero back pressure..)

Against 2 inches backpressure, that fan can only push about 17 CFM

You could wind up in a situation where the heating from the fan is more than whatever it's cooling.

Jim Lux


-----Original Message-----
From: beowulf-bounces at beowulf.org [mailto:beowulf-bounces at beowulf.org] On Behalf Of Mark Hahn
Sent: Friday, January 18, 2013 12:00 PM
To: Beowulf Mailing List
Subject: Re: [Beowulf] AMD Roadrunner open compute motherboard

> As in contradiction to what Mark Hahn says - it needs active cooling.

if anyone cares: a dimm dissipates roughly 2W, depending on generation, whether it's LV, number of devices, etc.  one of those duplex 14krpm fans is typically rated at about 12W.

in a mainstream server, each CPU will dissipate around 100W.
typical SATA disks, about 5W.  since servers normally have "platinum"
plus80 ratings these days, the PSU would need to dissipate ~30W.
NICs are normally <= 8W.

so even a 1W device needs some airflow, but it's mostly CPUs that count.
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