Originally Posted by barracks510
I understand your argument, but if you read the document again, you will see that there was no mention of idle temperatures, or etc. . Because I was aiming for scientific accuracy, I was limited to one variable - the choice of TIM - and one dependent - the performance of the processor. For the purposes of accuracy, the ambient temperatures were held at a constant 20°C, and the load temperatures were also held constant. Because the only time the load temperatures would be at a constant is the point of TJMax (67.7° in this case), I took advantage of Intel's thermal throttling technology to keep it there.
Granted, you may find this a test of the cooling solution, but as I already explained, all temperatures were held constant. I believed that using a more effective (temperature-wise) TIM would increase the "overhead" performance, so to speak, allowing the proccessor to have more computed before hitting a thermal throttling cycle.
Hi Barracks, my comments weren't directed at your research but more a general comment and this seemed a relevant thread to air those views.....but having said that I've re read your pdf more thoroughly.....I'm not 100% sure I've fully understood but if the performance results you have published are the resultant performance following thermal throttling of the cpu then they are indeed related to temperature albeit in a slightly more convoluted manner.......so in essence I think my previous post would apply to your results also....if the thermal capabilities of the heat sink are not large in comparison to the heat transfer capabilities of the TIM then the differences in the TIM may be masked.
It's possible that by artificially lowering the heat load by imposing the 55c throttling limit that that you have started to see the differences in the Tim performance and possibly why the ceramic was starting to push ahead.....but even at this lowered heat level I think the thermal performance of the heat sink assembly may well be affecting results.....I think for reliable TIM testing a very powerful cooling solution would be required so that it's effects on results would be negligible.
If I may be so bold as to offer critique I believe one aspect of your testing that may have introduced error was the use of alcohol which I presume was ethanol as the carrier for the various conductive particles.
Firstly this may well be evaporating, phase changing if you will, and so altering temperatures.
Secondly this effect may not be equal in all three particle suspensions, ceramic and aluminium (actually the outer coating of your aluminium particles will be invariably aluminium oxide due to it's reactivity with atmospheric oxygen) being very polar or highly charged in their chemical nature would tend to hold the alcohol more strongly due to hydrogen bonding with the alcohol where as diamond being non polar would tend to release it more readily.
Thirdly for the very same reasons heat exchange within the TIM between the particles and carrier alcohol would be favored in the case of ceramic and aluminium because of their stronger interaction with the alcohol while the lesser interaction of the alcohol with the diamond would hinder internal heat transfer in that case.
All interesting research though and a definite step in the right direction for a better means of testing TIM in my opinion, simply restricting the heat load seems to have shown some differentiation in the results......now what about trying it with an uber powerful cooling method?