[conspire] Last Year's Supercomputer

[Mark S Bilk]

In-Reply-To: <20030609094831.GV29461 at linuxmafia.com>; from rick at linuxmafia.com on Mon, Jun 09, 2003 at 02:48:31AM -0700

On Mon, Jun 09, 2003 at 02:48:31AM -0700, Rick Moen wrote:
>Quoting Mark S Bilk (mark at cosmicpenguin.com):
>
>> The usual technique for cooling is to blow a lot of air through
>> the case in order to get a small fraction of it flowing past 
>> the few parts that get very hot.  This requires powerful, noisy
>> fans.
>> 
>> My solution is to hang a small fan right up against each hot
>> device.  I get them from Halte[k|d] -- 6cm x 6cm, 12V, 1watt,
>> about $7, absolutely silent.
>
>See, that's good, but I think one can do better.  With careful system
>design and parts selection, it's possible to do mostly passive cooling,
>where conduction via adjacent metal, convection of air through a
>spacious case, and scrupulous spacing out of the problem components
>keeps things from overheating.  I don't know about you, but I'd feel
>really dumb replacing a $200 part (say, your pride-and-joy large hard
>drive) just because a $7 fan failed.

True, but that's always the case with the CPU heatsink fan.
Well, I guess there are thermal sensors these days that 
might save the chip.

OK, I guess I should get a full-size tower.  It will only take 
up another inch or two of width on my desk, and then I can space
the disk drives as you say.  If the cpu's fan seizes up and it
melts, I'm only out $100, and no data lost, as from a dead disk.

And I really don't want to reuse the old mini-tower, because it
will still be a functioning system, if I put the video card back 
in, or get a $10 one, and I have two 4G used SCSI drives that
I bought for swap service.  With both in there it will have 
plenty of disk for a functioning system.  Who knows, it might 
come in handy some day, and it would be a shame to destroy it
just to take the case.

>Just before the dot-com crash, we had an example of forced-air cooling
>run amok that I regard as an excellent cautionary tale.  My
>then-employer was, I believe, the first firm to release a dual-Athlon
>rack-mount 2U server system.  It drew ridiculous amounts of electical
>power, almost all of which of course eventually got radiated out as
>heat.  To prevent it from melting down, a hell of a lot of air got
>driven through the chassis from front to back, and the case itself was
>of careful (patented) design to maximise the benefit of all that
>airflow.  We sold clusters of those damned things for scientific
>computing, and the sorts of labs that bought them had to bring in
>extra-heavy-duty power feeds for them -- not to mention air
>conditioning.  And the din they put out was just unbelievable!

Yiii!

>I wouldn't have taken one on a bet, and I'll bet that just the AC power
>and air conditioning bills for a cluster of them would break the bank.
>I wonder if they're still in use, anywhere?
>
>So, anyway, the aforementioned K6 tower is my preferred sort of system.
>It's relatively quiet, and probably _could_ get by on almost entirely
>passive cooling, because of the huge case and large amounts of spacing
>between the heat-producing components (which, on reflection, means
>mostly the two hard drives).  

Well see, that's kind of like my open-case method.  The whole room
is my big case!  But I certainly take your point.

>I have a couple of case fans on the
>belt-and-suspenders theory.  It would be _quieter_ without them, and could
>probably survive without them and with a PC Power & Cooling Silencer
>instead of the big-ass TurboCool.  But it's relatively quiet and runs 
>very cool, while giving me the confidence that it would remain OK even
>if a couple of the fans seized up.

Do you think a Silencer would provide enough power for my system?

>> I have one blowing on the Riva TNT graphic card, one on the
>> soon-to-be-retired swap drive, and one on the two main 3.5" drives
>> that are stacked only 1/8" apart.  
>
>See, that bit about 1/8" spacing sounds bad, to me.  I'd stretch out the
>spacing a lot, if possible.  If the case didn't permit that, I'd shitcan
>the case and get a bigger one.  In fact, that's exactly what I _did_ do,
>to get the case the K6 now resides in.

OK.  Now I have two good reasons not to recyle the mini-tower!

Are there towers where you can adjust the spacing between the 
disks, like by having tapped holes every half inch or so, instead
of fixed bays?

>I'm not in any way saying you haven't done a great job.  What matters is
>results, and you say it runs cool.  That counts as success.  However,
>you've achieved that at the cost of making the cooling reliant on a
>bunch of $7 fans.  I get greater warm-fuzzies from removing that
>reliance, is all I'm saying.
>
>> I haven't had the side panel on the case for years....
>
>Most cases are actually designed so that they do effective air flow only
>with the case closed.  You may be impairing heat control, by operating
>it that way.

I know, but I did feel up all the parts to make sure they're cool 
enough, and the power supply fan is still blowing right on the cpu
and memory.  

All right, I will try to keep the case buttoned up on the new one, 
if the cpu stays cool enough.

Well, maybe...  I think I'm going to want to _look_ at it a lot!

  Thanks!
  
  Mark