Hi, folks,
I'm installing a RAID controller card for a large external RAID box in
a Dell server. I've got two riser slots available. Here's the question:
the controller card has some large chips on one side, and if I put it
in riser 1, those chips face downwards in the box, blocking ease of
cooling, while if I put it in riser 2, the chips will face up... but be
right over a large chip on the m/b that's got a heat sink.
Opinions on which slot to use?
mark
On 9/16/2014 13:29, m.roth at 5-cent.us wrote:> > Opinions on which slot to use?My opinion is that you should read "Hot Air Rises and Heat Sinks: Everything You Know About Cooling Electronics Is Wrong" by Tony Kordyban. It is quite readable, for all that it is a serious EE book. Thermal dynamics is not a matter of opinion. Either someone is giving you a guess, in which case you have to decide if they're likely to do better than chance, or they have done the experiment or thermal modeling, in which case they aren't offering either a guess or an opinion. You could just assume Dell has already worked through the thermal dynamics and has provided enough cooling headroom that both slots can be used with hot cards. If you've found that they don't fight you on warranty replacements for cooked mobos or third-party cards, go ahead and take a guess. Or, you can do the experiment yourself. You have the equipment, you have the environment, and you have lm_sensors. Try it both ways, and let us know what you find. When your boss asks you why you are faffing about with R, tell him it's For Science! You do research there, right? Here you are, doing research, and you didn't even have to get a grant to do it. There's your science in the public interest, Mr Bossman!
On Tue, September 16, 2014 2:29 pm, m.roth at 5-cent.us wrote:> Hi, folks, > > I'm installing a RAID controller card for a large external RAID box in > a Dell server. I've got two riser slots available. Here's the question: > the controller card has some large chips on one side, and if I put it > in riser 1, those chips face downwards in the box, blocking ease of > cooling, while if I put it in riser 2, the chips will face up... but be > right over a large chip on the m/b that's got a heat sink. >I would use riser 1. If you use riser 2, you will create more resistance to airflow in area where already is one big heater. I assume, there are no separators of airflow going from front to end (or from middle where the set of fans are usually situated). My guess would be chips facing down have much less effect on effectiveness of cooling unless your configuration is such that airflow path along chips (i.e. underneath that board in riser 1) is totally blocked. Valeri ++++++++++++++++++++++++++++++++++++++++ Valeri Galtsev Sr System Administrator Department of Astronomy and Astrophysics Kavli Institute for Cosmological Physics University of Chicago Phone: 773-702-4247 ++++++++++++++++++++++++++++++++++++++++