Dual AMD systems in rackmount cases

Joel Jaeggli joelja at darkwing.uoregon.edu
Mon Jun 24 11:46:26 PDT 2002

On Mon, 24 Jun 2002, Mark Hahn wrote:

> > > Does anybody have any experience with Dual AMD systems (MP2000) in 2 RU
> > > rackmount cases?  Is heat generation a problem?  I am planning on
> there seem to be quite a lot of vendors who seem confident enough
> to sell dual AMD 1U's.  I don't see a lot of 2U's; my impression
> is that the engineering for such boxes is strictly based on flow,
> and that the increased dead-air capacity of 2U doesn't buy you much.

it buys you the ability to use 80mm fans, reasonable sized power supplies 
and decent sized heatsinks. with heatsinks with side-mounted fans such as 
the alpha pep66u the size of the unit you can put in a 2u case is quite 
large. the supermicro 6022 (dual p4) we have do exactly that... 
> > > building a system with Tyan 2466 motherboards and 400 W power
> > > supplies.  Should I use 3RU cases?
> if you can afford the lower density, go for it!  is 3U high enough
> to handle normal upright PCI cards? 

3u is,  5.25", 2u (3.5")is tall enough to use low-profile pci cards 
directy in slots with a properly designed case of which the supermicro 
6022p (not athlon but a good example) is one variety


 risers for low-profile cases
> appear to be a source of some difficulty...
> racksaver, for instance, seems comfortable letting you configure 
> a dual athMP/2100 right now.  apparently the thoroughbred version
> will save just a handful of wats.
> > As important as these two components is being able to provide ambient
> > air at around 65F (or cooler, of course:-) on the air intake side of the
> > cases and to get rid of the 75F air coming out of the air outflow side
> 75 seems a little conservative on exhaust temp, though I suppose it 
> depends hugely on the volume of air you're talking about.  my machineroom
> (currently 30 KW of alphas, but soon to have 5-10KW new ia32's)
> registers around 60-65 in the cold ducts, and around 85 in return.
> and, importantly I think, there's a pretty clear and strong airflow
> pattern.
> > Dual AMD's will just plain crash when they get hot, and they get hot
> > very, very easily as they draw about 150 W sustained under load.  In our
> AMD's pushing vendors to implement thermal management, but I'm not 
> clear on how well it all works.
> > new server room, our 2U cases were not originally getting enough, cold
> > enough, air and the temperature at the case rears was up in the 80's.
> it depends on how "dilluted" that 80F is - by itself, 80F is still
> quite cool: suppose you have a CPU dissipating 70W, and your HS/fan
> will need 20-25C of thermal gradient.  since you don't want your CPU
> at its rated max (usually 90C), but say 60C, you need fan ambient
> to be 95F or less.
> > KW/meter^3 seems unwise -- any sort of bobble in your cooling system
> > will rapidly cause your stack to reach furnace temperatures, and even
> ah, well, I think you have to start with assuming *something* stays up.
> I'm assuming that I can shut down my space heaters if (when) our chilled
> water goes out (again)...
> regards, mark hahn.
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Joel Jaeggli	      Academic User Services   joelja at darkwing.uoregon.edu    
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