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EMC2 · 03-28-2002, 06:59 PM

Ok - I can agree completely with your points depending upon what your intended goal is

Now let's look at in from another perspective - take the secondary cooling paths. If one is really trying to see how well a block performs in a system in comparison to other blocks then shouldn't you also take those secondary cooling paths into account? Or what about other variables that you have "in system" that you don't have with a die simulator?

Part of the above invokes the question of what are you trying to really test? Is it the performance of one block to another? Is it the measurement of deltaT between inlet coolant and die temps (as some would say a "bastardized" C/W)?
Or maybe it is how well a CPU will OC with one cooling method over another? Part of the issue here - is the entire die surface uniformly cooled or are there hotter areas with one method or another? What about reaction to load change? How quickly does the cooling device respond, are there any short duration temperature spikes?

I also completely agree, no matter what the intent of the testing is, that the thermal interface between the die and the CPU is the most troubling one in some ways (for that matter between the temperature measuring device and any solid object). That having been said, there is a possible way around that problem in the case of the wb/die interface, depending upon what the intended testing goal is. I know you'll probably make faces at this one, but give the thought a whirl before you reject it

You pretty well addressed the issues of using thermal compound at the wb/die interface (thickness, aging, batch to batch variations - with thickness/application being the biggest headache within a given testing sequence). What about using something that doesn't vary as much - but - isn't as thermally conductive? In this case - one of Thermagon's conductive foams. Controlled thickness (always the same if you use the same piece of foam and same compression force and it's reusable). It would significant reduce the variability at the wb/die interface. (note - I am not suggesting it's use for an actual system on a day to day basis because of the C/W rating of it, just as a tool to help eliminate some of the issues of thermal compound for a test environment).

Oh - and a wild thought about the differences in the temp measurements on that Duron you mentioned - were there heat producing components in the "well of the socket" that were affecting your readings? (like resistors)

03-28-2002, 06:59 PM	#78
EMC2 Cooling Savant Join Date: Feb 2002 Location: Dark Side of the Moon Posts: 365	Ok - I can agree completely with your points depending upon what your intended goal is Now let's look at in from another perspective - take the secondary cooling paths. If one is really trying to see how well a block performs in a system in comparison to other blocks then shouldn't you also take those secondary cooling paths into account? Or what about other variables that you have "in system" that you don't have with a die simulator? Part of the above invokes the question of what are you trying to really test? Is it the performance of one block to another? Is it the measurement of deltaT between inlet coolant and die temps (as some would say a "bastardized" C/W)? Or maybe it is how well a CPU will OC with one cooling method over another? Part of the issue here - is the entire die surface uniformly cooled or are there hotter areas with one method or another? What about reaction to load change? How quickly does the cooling device respond, are there any short duration temperature spikes? I also completely agree, no matter what the intent of the testing is, that the thermal interface between the die and the CPU is the most troubling one in some ways (for that matter between the temperature measuring device and any solid object). That having been said, there is a possible way around that problem in the case of the wb/die interface, depending upon what the intended testing goal is. I know you'll probably make faces at this one, but give the thought a whirl before you reject it You pretty well addressed the issues of using thermal compound at the wb/die interface (thickness, aging, batch to batch variations - with thickness/application being the biggest headache within a given testing sequence). What about using something that doesn't vary as much - but - isn't as thermally conductive? In this case - one of Thermagon's conductive foams. Controlled thickness (always the same if you use the same piece of foam and same compression force and it's reusable). It would significant reduce the variability at the wb/die interface. (note - I am not suggesting it's use for an actual system on a day to day basis because of the C/W rating of it, just as a tool to help eliminate some of the issues of thermal compound for a test environment). Oh - and a wild thought about the differences in the temp measurements on that Duron you mentioned - were there heat producing components in the "well of the socket" that were affecting your readings? (like resistors)