<HTML><BODY style="word-wrap: break-word; -khtml-nbsp-mode: space; -khtml-line-break: after-white-space; "><BR><DIV><DIV>On Mar 3, 2006, at 12:53 PM, <A href="mailto:beowulf-request@beowulf.org">beowulf-request@beowulf.org</A> wrote:</DIV><BR class="Apple-interchange-newline"><BLOCKQUOTE type="cite"><P style="margin: 0.0px 0.0px 0.0px 0.0px"><FONT face="Lucida Grande" size="4" style="font: 13.0px Lucida Grande">O.K. So<SPAN class="Apple-converted-space"> </SPAN>Option 3 -- 32 desktops from HP or Dell-- is eliminated because </FONT><FONT face="Lucida Grande" size="4" style="font: 13.0px Lucida Grande">I cannot afford to upgrade the air conditioning unit in the room</FONT></P> <P style="margin: 0.0px 0.0px 0.0px 0.0px"><FONT face="Lucida Grande" size="4" style="font: 13.0px Lucida Grande">available and I cannot afford an onsite service contract to cover repair </FONT><FONT face="Lucida Grande" size="4" style="font: 13.0px Lucida Grande">costs.<SPAN class="Apple-converted-space"> </SPAN></FONT></P></BLOCKQUOTE><DIV><BR class="khtml-block-placeholder"></DIV><DIV>Trade offs: air conditioning or service contract or both? Without a good cool air source (colder than ambient temp), the service contract becomes almost mandatory. If you can engineer great ventilation with lots of cooler air entering the farm, you might be able to skate on both air conditioning and service contracts. Change the room air 2 to 4 times per hour or keep ambient room air from exceeding 90 F. with reasonable good circulation around the systems. Sometimes a good, easily opened sky light with a good sized exhaust fan will solve a world of circulation problems. Paying attention to the original heat load generation will save huge amounts of expense.</DIV><DIV>Often overlooked: extra large CPU power supplies run cooler. If standard power supplies run warm to the touch (100 F. +), upgrading to 50 % larger will reduce heat loads (300 watt upgraded to 450 watt supply). A CPU that only needs 200 watts will only consume that 200 watts, no matter the size of the supply ... and a 300 watt supply "stressed" to 60% of rated load will run warm, but a 450 watt supply running at 45% of rated duty will not produce nearly as much heat ... and the larger will last longer. (Alternative below)</DIV><DIV>Sometimes overlooked: larger, older monitors run warmer than small ones or cheap flat screen LCD monitors. (Big monitors are needed only to sell the next round of grant refinancing. :>) </DIV><DIV>Not to be ignored: Larger gauge power wires are cooler. This may seem like micromanagement, but 32 systems feed by 32 sets of #16 gauge plug strips and power lines will also generate some heat. Spending 10% more for fewer #12 gauge power feeds might save enough to be important. Healthier power / surge strips, larger circuit breakers = same, same.</DIV><BR><BLOCKQUOTE type="cite"><P style="margin: 0.0px 0.0px 0.0px 0.0px"><FONT face="Lucida Grande" size="4" style="font: 13.0px Lucida Grande">In response to RGB's request for more information: </FONT><FONT face="Lucida Grande" size="4" style="font: 13.0px Lucida Grande">Here are my budgetary constraints and my needs</FONT></P> <P style="margin: 0.0px 0.0px 0.0px 0.0px; font: 13.0px Lucida Grande; min-height: 16.0px"><BR></P> <P style="margin: 0.0px 0.0px 0.0px 0.0px"><FONT face="Lucida Grande" size="4" style="font: 13.0px Lucida Grande">Budget ~US $25K, with the possibility of $5K ...</FONT><FONT face="Lucida Grande" size="4" style="font: 13.0px Lucida Grande"><SPAN class="Apple-converted-space"> </SPAN>My simulations</FONT><FONT face="Lucida Grande" size="4" style="font: 13.0px Lucida Grande"> ... </FONT><FONT face="Lucida Grande" size="4" style="font: 13.0px Lucida Grande">require in excess of 512 MB of memory ...</FONT><FONT face="Lucida Grande" size="4" style="font: 13.0px Lucida Grande"> ideally twice </FONT><FONT face="Lucida Grande" size="4" style="font: 13.0px Lucida Grande">that amount. ... </FONT><FONT face="Lucida Grande" size="4" style="font: 13.0px Lucida Grande">should go for gigabit ethernet.</FONT></P> </BLOCKQUOTE><BR></DIV><DIV>Yes ... 32 CPUs w/ 512K RAM plus several flat screen monitors. Assuming ISA style "mini tower" boxes, 2 to 3 GigaHertz each, would have a total heat load requirement of around 6000 watts (running) ... could be offset by two window mounted air conditioners ... US$400 to $500 x 32 = US$12K to US$16K+, plus accessories and power lines and air conditioning and installation and service, etc., etc. ... quite possibly a budget buster.</DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV>A possible alternative: Last week Apple announced the newer version of the Mac Mini ... meaning that the previous models could shortly be picked up quite reasonably ... and picking up a number of these [1.25 or 1.4 GigaHertz, 512K RAM (upgradable), ethernet and FireWire equipped, 50 watt (observed, running)] systems ... is certainly food for thought ... as the FireWire ports as fast or faster than 1000baseT ethernet and work with Apple's own "beowulf scenario" (<A href="http://www.apple.com/xserve/workgroupcluster/">http://www.apple.com/xserve/workgroupcluster/</A>) or if preferred a Linux variant ( yellowdoglinux.com / terrasoftsolutions.com ).</DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV>And the heat load of 32 of these could be resolved with a window fan and a maintenance contract could be resolved by getting some spares ... :>)</DIV><BR><DIV> <P style="margin: 0.0px 0.0px 0.0px 0.0px; font: 13.0px Lucida Grande">Ed Karns</P><P style="margin: 0.0px 0.0px 0.0px 0.0px; font: 13.0px Lucida Grande">FireWireStuff.com</P><BR class="Apple-interchange-newline"> </DIV></BODY></HTML>