Ernest L. Gunerius wrote: >> On 14/3/09 02:32, "Wallace Adrian D'Alessio" <[email protected]> >> wrote: >> >> > Overclockers who are set on defeating heat to preserve costly CPUs >> yet squeeze >> > extreme clock counts out of them have been known to polish the CPU and >> > heatsink with ever finer grades of wet or dry paper starting with >> 1000 grit. >> > And even going to finer grits of polishing compound. Some may even " >> lap : the >> > surfaces together with a polishing compound. >> > >> > Then they apply the thermal paste after all of that. >> > >> > In theory the more closely the parts surfaces match and the thinner >> the paste >> > needed to >> > make up the difference the faster and therefore the more successful >> the heat >> > transfer will be. >> > >> >> Seems strange - the laws of physics would suggest that a coarse >> finish - >> rather than a polished surface - would provide a much greater surface area >> for a face to face contact - with the compound filling the pits in the >> coarse finish... > >> Pete > >> ~------~--~--- > > > With a coarse finish the surfaces are held apart by the metal to metal > contact at random spots and the interstices are filed with compound. The > compound has a finite, even if small, Thermal resistance. The length of > the path through the compound is defined by the roughness of the surfaces. > > The smoother the surface the smaller the interstices left by the metal > to metal contact points. Thus the layer of Compound necessary to fill > the interstices is thinner. > > It could be argued and possibly answered by experiment that there could > be a surface condition in the range between a very rough finish and a > finish that imposes a Casimir force that would give the minimum thermal > resistance at a reasonable cost of Time, Money and Resources. > > I would imagine that the Engineers at the Heat sink, Thermal Paste, > Processor and Computer Manufacturers have thoroughly investigated the > situation. > > If they have followed good engineering practices they have experimented > and found a workable solution within the Triple Constraint (Money, > Resources, Time). > > The Over Clockers are the modern equivalent of the old Shade Tree > Mechanics squeezing the last possible Horsepower/Torque out of a Flat > Head Ford engine; as they work within their version of the Triple > Constraint. > > If it works for them, Hurrah, > > ErnieG >
Heh... You mean the engine that despite having two waterpumps still tended to overheat? <G> JT --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed Low End Mac's G3-5 List, a group for those using G3, G4, and G5 desktop Macs - with a particular focus on Power Macs. The list FAQ is at http://lowendmac.com/lists/g-list.shtml and our netiquette guide is at http://www.lowendmac.com/lists/netiquette.shtml To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/g3-5-list?hl=en Low End Mac RSS feed at feed://lowendmac.com/feed.xml -~----------~----~----~----~------~----~------~--~---
