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#61
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"David Maynard" wrote in message
... Ya know, measuring the distance between stars in inches isn't really practical but if you're off by .1 parsecs when you get there that last step off the ladder ain't going to be just 'one small step for a man' whether it's a "single digit number" or not. LOL :-) [UK]_Nick... |
#62
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w_tom wrote:
Dansdata.com does provide a watts number. Unfortunately it must calculated from his data. The only numbers provided are C/W. Neither watts or temperatures are derivable from those numbers. I believe it was also provided in another article about this same test. There wasn't a link to 'another' article and I can only go by what was there. He did, however, mention he changed it from his 'normal' setup. He was using a constant 50 watt heat source which is typically equivalent to a 65 or 75 watt CPU. A 'what' CPU? Both AMD and Intel give power dissipation requirements and the maximum for an AMD XP3200 is 76.8 Watts. The thermal design power spec for an Intel 3.06 Gig is 81.8 watts. That's straight HEAT, not some 'typically equivalent' invention of yours. My example with 70 watts was not out of range, not to mention I included numbers for 55W and 35W (35W being about right for a 1.4 gig tualatin celeron). From his data, thermal compounds resulted in a 9 degree reduction of CPU temperature. Not from the data in THAT article. As kony has demonstrated, this would probably be less if the heatsink was smooth; not concentric rings. Probably, but that doesn't alter the fact that your characterization of what HE said is inaccurate. And there was virtually no difference between Arctic Silver and all other thermal compounds. Which, btw, were all 'grease' type materials in that they were not pads (the topic of this thread) It's also not the topic you keep trying to promulgate. But demonstrated is that thermal compound only results in, at best, single digit temperature reductions. False, and I posted the numbers which prove it. Take the top end XP or P4 power numbers and it would be even larger than the BIGGER THAN A SINGLE DIGIT one I posted for 70 watts. Not to mention all I have to do is state temperatures in F to ruin your 'single digit numbers' claim for 9C. Even with a worse case heatsink surface of concentric rings (not smooth), the thermal compound only resulted in single digit temperature decrease. Thermal compound would only be less effective had that heatsink surface been smooth. And I've posted specific, and numerical, analysis of thermal budgets which show 'single digit numbers' are significant. I would have though my .1 parsec joke would have driven home the point that broad brush euphemisms like 'single digit number' don't mean anything. David Maynard wrote: You misrepresent the data. The bare heatsink came in at 0.66°C/W and with thermal compound down to 0.48°C/W but the article provided no watt numbers for his test setup from which to derive any actual temperatures. If we plug a 70 watt CPU into those numbers the temperature improvement would be 12.6C and not your claim of "only single digit temperature improvements." One has to get below 55.5 watts to be under a 10C improvement. A 35 watt CPU would get a 6.3C improvement but, as I've shown by actual thermal budget calculations, "single digit temperature improvements" ARE significant. And I reiterate one of them he My current CPU is running at 44C in a 33C case ambient. That's a total 11C rise and even 6.3 would represent more than HALF (57.2%) the heatsink's job. Again, I'm not saying those are the numbers in my setup but that something simply being a "single digit number" does not make it insignificant. His data and conclusions had nothing to do with claiming thermal compound was unnecessary. To the contrary, he opened with an explanation of why it is. His conclusion was that one would not see a dramatic improvement when going from 'plain ole' thermal compound to expensive, supposedly 'hi tech', compounds as the difference between THEM was not 'large'. With that I agree. Air is some 3,000 times a worse thermal conductor than aluminum. Now, thermal compound is no where near as good as aluminum either but it's a heck of a lot better than air so the improvement over an air gap is large. However, once that initial 'barrier' has been filled, the variation in thermal resistance from one compound to the next isn't much in the overall picture as the lion's share of the improvement has already been accomplished by filling the gap with almost anything having a half way decent thermal conductance. ... We are all aware that the surface characteristics affect thermal performance. As a side note, his 'mission' to explain how statistics can lie is well and good enough in that one can use statistics to lie but it would be better stated as using a PROPER scale rather than his apparent affinity for '0' as the universal and 'true' meaningful point of origin. For example, if we used Kelvin as the temperature scale, starting at absolute zero of course, then the entire normal operating range of a typical PC, e.g. 5C to ~40C, looks 'insignificant', using his term of "10%" (or less), but then that's the range we typically work in. Similarly, when looking at rise above ambient, ambient is the more appropriate baseline, not '0', as one cannot cool below ambient (without active devices, that is). His '10%' rule of thumb suffers from the same lack of an 'appropriateness' criteria. If one were to take it as a universal rule then the ATX power spec is 'insignificant' as it requires 3.3 and 5 volts to be held within 5% but clearly, those voltages being off an 'insignificant' 9% is not 'insignificant'; which, btw, mirrors my complaint with your constant insistence that "single digit numbers" somehow don't ever 'count' for anything. By your reckoning, an ATX PSU's 5v and 3.3 volt rails don't count, and neither does the processor's Vcore, as they're all no more than a 'single digit' above the decimal point. They might as well all be 3 volts since that's not more than an 'insignificant' "single digit number," 2, away from any of them, right? Buy a dozen eggs that are off by a measly, 'single digit number', 8.3 percent and you're not going to be too happy about getting 11 eggs instead of 12. Say the computer manufacturer specs your machine to 40C but it crashes at 31C. Hey, that 9C difference is only a 'single digit number' so you're happy, right? Which, speaking of appropriateness and scales, brings us to units of measurement e.g. 9C is 16.2F. Hey, 16.2 is more that a 'single digit number so 16.2 is significant, but 9 isn't... but 16.2 is... but 9 isn't... but Ya know, measuring the distance between stars in inches isn't really practical but if you're off by .1 parsecs when you get there that last step off the ladder ain't going to be just 'one small step for a man' whether it's a "single digit number" or not. |
#63
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A 65 or 75 watt CPU typically outputs about 50 watts. One
with numerical experience and heatsinks would know this. David Maynard is only just learning these numbers exist. So he posts this in error: If we plug a 70 watt CPU into those numbers the temperature improvement would be 12.6C 0.66 - 0.48 is 0.18. A 70 watt CPU (maximum power) outputs typically about 46 to 52 watts; or 50 watts. David would know this if he had heatsink design experience. 9 degree difference - a single digit difference. And that difference would be even smaller if tested heatsink provided a better interface surface as kong demonstrated. A better heatsink surface means even higher wattage CPUs still only output single digit temperature differences - not important to the average CPU user. David Maynard assumes a 70 watt CPU outputs 70 watts constant because these numbers and calculations are new to him. IOW he wants to argue. Fact stated - thermal compound only results in single digit temperature decreases. Dansdata.com demonstrates same using a heatsink that does not even have a good surface. With or without thermal compound are both valid options when assembling a CPU to heatsink. Either will provide sufficient CPU cooling even if run on a 100 degree F room. Important is the 'degree C per watt' rating on that heatsink - use of thermal compound is but a secondary consideration. kony demonstrated even less advantage to thermal compound when he lapped a heatsink surface. Bottom line, thermal compound makes but a minor temperature improvement - which is contrary to many widely touted legends. A 9 degree difference is not significant - except when overclocking. Those nine degrees would be even less using a heatsink with better surface. That was posted previously which leaves me to wonder why so much naysaying - without supporting facts - and without comprehending a difference between typical and maximum CPU watts. I am left to assume another only wants to argue. Dansdata.com demonstrates what kony also demonstrated and what is obvious from calculations. Thermal compound is not essential to CPU operations - except maybe for the overclocker. Following points were summarized in a post on 7 Sept, and are posted again for the benefit of lurkers who have been confused by all this naysaying supporting facts or correct numbers: 1) that thermal compound must be applied so sparingly that CPU makes mostly a direct contact with heatsink. So little thermal compound that it does not spread much into the outer half of CPU. 2) if heatsink is properly machined, then heatsink can be applied to CPU without any thermal compound. If properly machined, then thermal compound would only result in single digit temperature decreases. 3) many heatsinks are sold even without the essential "degree C per watt" number. Many don't even know how good their heatsink really is OR how much better it would be if properly mated to CPU. That test first without thermal compound, then with goes a long way to learning how good a heatsink really is. 4) Arctic Silver is overhyped. Most thermal compounds do for dimes what Arctic Silver does for dollars. But then Arctic Silver also does not make numerical specifications easily available - which should be the first indicator that Arctic Silver is hiding something. Products sold without numerical specs should be routinely suspect. Arctic Silver is mostly sold on hype - engineering specs be damned when your customers too often fear the numbers. David Maynard wrote: w_tom wrote: Dansdata.com does provide a watts number. Unfortunately it must calculated from his data. The only numbers provided are C/W. Neither watts or temperatures are derivable from those numbers. I believe it was also provided in another article about this same test. There wasn't a link to 'another' article and I can only go by what was there. He did, however, mention he changed it from his 'normal' setup. He was using a constant 50 watt heat source which is typically equivalent to a 65 or 75 watt CPU. A 'what' CPU? Both AMD and Intel give power dissipation requirements and the maximum for an AMD XP3200 is 76.8 Watts. The thermal design power spec for an Intel 3.06 Gig is 81.8 watts. That's straight HEAT, not some 'typically equivalent' invention of yours. My example with 70 watts was not out of range, not to mention I included numbers for 55W and 35W (35W being about right for a 1.4 gig tualatin celeron). From his data, thermal compounds resulted in a 9 degree reduction of CPU temperature. Not from the data in THAT article. As kony has demonstrated, this would probably be less if the heatsink was smooth; not concentric rings. Probably, but that doesn't alter the fact that your characterization of what HE said is inaccurate. And there was virtually no difference between Arctic Silver and all other thermal compounds. Which, btw, were all 'grease' type materials in that they were not pads (the topic of this thread) It's also not the topic you keep trying to promulgate. But demonstrated is that thermal compound only results in, at best, single digit temperature reductions. False, and I posted the numbers which prove it. Take the top end XP or P4 power numbers and it would be even larger than the BIGGER THAN A SINGLE DIGIT one I posted for 70 watts. Not to mention all I have to do is state temperatures in F to ruin your 'single digit numbers' claim for 9C. Even with a worse case heatsink surface of concentric rings (not smooth), the thermal compound only resulted in single digit temperature decrease. Thermal compound would only be less effective had that heatsink surface been smooth. And I've posted specific, and numerical, analysis of thermal budgets which show 'single digit numbers' are significant. I would have though my .1 parsec joke would have driven home the point that broad brush euphemisms like 'single digit number' don't mean anything. |
#64
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w_tom wrote:
A 65 or 75 watt CPU typically outputs about 50 watts. One with numerical experience and heatsinks would know this. David Maynard is only just learning these numbers exist. Maybe some day you'll learn to read a spec sheet before you make an even bigger fool of yourself than you have already. Intel® Pentium® 4 Processor with 512-KB L2 Cache on 0.13 Micron Process: April 2003 Document Number: 298643-008 5.1 Thermal Specifications Table 5-1 specifies the thermal design power dissipation envelope for the Pentium 4 processor with 512-KB L2 cache on 0.13 micron process. Table 5-1. Processor Thermal Design Power Processors with Thermal Design multiple VIDs Power1,2 (W) .. .. .. 3.06 GHz 81.8 Processors with multiple VIDs for 800 MHz system bus .. .. .. 3 GHz 81.9 That's heat dissipation the thermal solution should be capable of handling. It is NOT the electrical power requirements, which I presume is what you think "70 watt CPU" means; those are in section 2.11. So he posts this in error: If we plug a 70 watt CPU into those numbers the temperature improvement would be 12.6C 0.66 - 0.48 is 0.18. A 70 watt CPU (maximum power) outputs typically about 46 to 52 watts; or 50 watts. I wasn't talking about whatever you think a "70 watt CPU (maximum power)" is. I told you specifically which ones, by manufacturer and model number, and the heat they generate according to the manufacturer's spec sheet; or can't you read? David would know this if he had heatsink design experience. 9 degree difference - a single digit difference. Wrong. .18C/W times 70 watts is 12.6C. As I said, if we used the Intel numbers for a 3.06 Gig P4, I.E. 81.8W, it would be even more. And if you weren't such an ass you'd have noticed I also included calculations for 55 watts and 35 watts to show what the numbers would be over a range of CPUs, and then showed their relevance to the thermal budget; even when "single digit". And that difference would be even smaller if tested heatsink provided a better interface surface as kong demonstrated. A better heatsink surface means even higher wattage CPUs still only output single digit temperature differences - not important to the average CPU user. It's only important if they want it to work per specifications. Of course, then there's the point that your incessant claim "single digit" numbers are "not important" is utter nonsense. David Maynard assumes a 70 watt CPU outputs 70 watts constant because these numbers and calculations are new to him. IOW he wants to argue. Wrong. I listed the specific CPUs and gave the manufacturer's number for their thermal dissipation, not based on them being an 'X watt CPU', in terms so clear that even a room temperature IQ could follow it so I don't know why you failed to grasp it. snip of repetition David Maynard wrote: w_tom wrote: Dansdata.com does provide a watts number. Unfortunately it must calculated from his data. The only numbers provided are C/W. Neither watts or temperatures are derivable from those numbers. I believe it was also provided in another article about this same test. There wasn't a link to 'another' article and I can only go by what was there. He did, however, mention he changed it from his 'normal' setup. He was using a constant 50 watt heat source which is typically equivalent to a 65 or 75 watt CPU. A 'what' CPU? Both AMD and Intel give power dissipation requirements and the maximum for an AMD XP3200 is 76.8 Watts. The thermal design power spec for an Intel 3.06 Gig is 81.8 watts. That's straight HEAT, not some 'typically equivalent' invention of yours. My example with 70 watts was not out of range, not to mention I included numbers for 55W and 35W (35W being about right for a 1.4 gig tualatin celeron). From his data, thermal compounds resulted in a 9 degree reduction of CPU temperature. Not from the data in THAT article. As kony has demonstrated, this would probably be less if the heatsink was smooth; not concentric rings. Probably, but that doesn't alter the fact that your characterization of what HE said is inaccurate. And there was virtually no difference between Arctic Silver and all other thermal compounds. Which, btw, were all 'grease' type materials in that they were not pads (the topic of this thread) It's also not the topic you keep trying to promulgate. But demonstrated is that thermal compound only results in, at best, single digit temperature reductions. False, and I posted the numbers which prove it. Take the top end XP or P4 power numbers and it would be even larger than the BIGGER THAN A SINGLE DIGIT one I posted for 70 watts. Not to mention all I have to do is state temperatures in F to ruin your 'single digit numbers' claim for 9C. Even with a worse case heatsink surface of concentric rings (not smooth), the thermal compound only resulted in single digit temperature decrease. Thermal compound would only be less effective had that heatsink surface been smooth. And I've posted specific, and numerical, analysis of thermal budgets which show 'single digit numbers' are significant. I would have though my .1 parsec joke would have driven home the point that broad brush euphemisms like 'single digit number' don't mean anything. |
#65
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w_tom wrote in message ...
Author provides numbers with his results for heatsink bare verses heatsink with thermal compounds: http://www.dansdata.com/goop.htm His copper heatsink also had concentric ridges which were not removed. And yet thermal compound resulted in only single digit temperature improvements. If thermal compound doesn't matter much, why do all CPU manufacturers include something like it with their retail boxed CPUs and heatsinks? The retail boxed AMD XP1800+ I bought last month cmae with a layer of phase change material on its heatsink, and my old 300 MHz Slot 1 Intel Celeron heatsink, which was installed at the factory, had grey grease on it. Both heatsinks were fairly flat, although I didn't measure this. |
#67
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Can you guarantee that one will mount every CPU properly? I
too would recommend hobbyists use thermal compound. The stuff is so cheap. So many computer assemblers make mistakes. Best to just tell them to always use thermal compound. However CPU manufacturers have provided some CPU heatsink assemblies without thermal compound when customer assembly was not required. Too many computer assemblers completely avoid numbers such as the essential "degree C per watt" parameter. Better to tell them to install thermal compound to help compensate for a poorly surfaced or not even machined heatsinks. To compensate for heatsinks erroneously selected on hype, price, or a useless parameter such as CFM. Just because cheap thermal compound is used does not prove that thermal compound is required. Furthermore, a recent Intel paper demonstrated little difference between thermal compound and bare 'heatsink to CPU' for high power semiconductors. In that same paper, Intel also demonstrated advantages of phase change material. But those numbers are beyond the scope of where this discussion has proceeded. This discussion demonstrates how to experiment - to learn heatsink interface quality by running without and then without thermal compound. This discussion debunks myths about thermal compound being 'essential' by providing both underlying theory and experimental examples. This discussion demonstrates why specifications are so important in thermal analysis and which specifications are important. A "degree C per watt" specification is more important than thermal compound. Specifications associated with that "degree C per watt" parameter demonstrate pros and cons of thermal pads, thermal compound, and heatsink quality. Nothing from Intel or AMD 'instructions for assemblers' proves that thermal compound is essential. If thermal compound was essential, then one would have easily provided those numbers days ago. larrymoencurly wrote: If thermal compound doesn't matter much, why do all CPU manufacturers include something like it with their retail boxed CPUs and heatsinks? The retail boxed AMD XP1800+ I bought last month cmae with a layer of phase change material on its heatsink, and my old 300 MHz Slot 1 Intel Celeron heatsink, which was installed at the factory, had grey grease on it. Both heatsinks were fairly flat, although I didn't measure this. |
#68
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Without specifications, that post is just another junk
science proclamation. But then too many use such junk science logic which also makes Arctic Silver so profitable for its manufacturer. Strontium wrote: Tom's an idiot. Any more questions? |
#69
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w_tom wrote in message ...
If thermal compound doesn't matter much, why do all CPU manufacturers include something like it with their retail boxed CPUs and heatsinks? my old 300 MHz Slot 1 Intel Celeron heatsink, which was installed at the factory, had grey grease on it. [Heatsink was] fairly flat, although I didn't measure this. Can you guarantee that one will mount every CPU properly? I too would recommend hobbyists use thermal compound. The stuff is so cheap. So many computer assemblers make mistakes. I don't think that it's even possible to mount a Pentium4 heatsink improperly because of the widely-spaced supports, and with an Athlon improper mounting either causes the center part to be cracked or the CPU to burn up right away because of a big gap with the heatsink. But what about the example I mentioned previously, where the Slot 1 Celeron came with a factory-installed heatsink with thermal compound on it? |
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