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Apple Computing Products:
macOS - Notebook Hardware
Rember on the MBP-Or, "how to cook an Apple"
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<blockquote data-quote="Geeky1" data-source="post: 505769" data-attributes="member: 34442"><p>It's conceivable that it could be a software issue, but to be honest I think it's highly unlikely, because memtest/rember would have to interfere with the CPU diode measurement in some way, and I've never seen a program do that. I've seen Motherboard Monitor (old PC hardware monitoring program) return implausible-sometimes impossible-values for temperatures, but only when the wrong board or sensor configuration was selected.</p><p></p><p>I'm not saying it's impossible that it's a software glitch, but I really feel that it's unlikely. If anything was going to cause weird temperature readings, it'd be running more than one hardware monitoring program at a time, which would create a potential for both programs to try to access the same sensor at the same time, that could then cause bogus readings. But my temperatures are the same regardless of whether Hardware Monitor or SMC Fan Control are running alone, or both are running together. I can't prove it conclusively, but I really, really, REALLY don't think this is a software problem. It just doesn't add up for me.</p><p></p><p>It's possible for a CPU to experience localized heating where one part of the die is significantly hotter than another. This is particularly true when the CPU has very, very poor contact with the heatsink base (as it seems to in many MBPs).</p><p></p><p>And, though I'm not an electrical engineer by any means, from what I've been given to understand Intel (and AMD) tends to put the on-die temperature diode in whatever area of the cpu will get the hottest (that'd be the logical place to put it). Which means that while I suppose that there's a chance that it's a software glitch (though I can't fathom how), my gut feeling is that it's more likely that the reading is accurate.</p><p></p><p>Why? A couple reasons...</p><ol> <li data-xf-list-type="ol">The MBP's fans will not necessarily speed up significantly with increased CPU load, meaning that it's not an accurate indicator of how hot the CPU is getting in all cases. As I mentioned, the sensors that control the fan speed appear to sense the heatpipe temperature, not the CPU temperature; this is supported by the fact that people have reported their fans running at full speed constantly if the thermistors on the heatpipe are not reconnected after disassembling the machine. <br /> <br /> Unfortunately, the thermistors on the heatpipes register temperatures much lower than the actual CPU/GPU/NB temperatures, likely thanks to poor contact between the CPU and the heatsink, thus the fans can sit at 2500rpms or whatever while the CPU cooks merrily away at 90*C.</li> <li data-xf-list-type="ol">The MBP has a known heat issue that, by all accounts, is traceable to an issue with the thermal interface between the CPU and the heatsink (and the amount of thermal grease Apple puts on these things is further evidence of a contact problem). Fullscreening the visualizer in iTunes will run both my current one and the one I had to exchange up past 90*C, and my grandmother's behaves similarly. Memtest is very, very hard on certain parts of the CPU, and this, combined with the thermal interface problem, could very well result in localized areas of the CPU die topping 100*C.</li> </ol><p></p><p>Ideally, someone with Windows XP installed on their MBP (I'm still trying to find any one of my XP CDs <img src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" class="smilie smilie--sprite smilie--sprite3" alt=":(" title="Frown :(" loading="lazy" data-shortname=":(" />) would download and run the Intel Thermal Analysis Tool and report how hot the CPU gets when the TAT is set to run both cores at 100% load. That program will produce more heat from the CPU than anything else I've come across-that's what Intel designed it to do. Supposedly (though I have no way of confirming it) it will make the processor dissipate at LEAST its TDP, if not slightly more. That'd give us an idea, I think, of how hot the CPU will get, realistically speaking.</p><p></p><p>It'd be even better if they scanned for artifacts in ATItool or ran rthdribl at the same time, as those programs will push the GPU pretty hard, and since the GPU and the CPU share a common heatsink... I'd be interested to see if that would generate results similar to Rember or not.</p></blockquote><p></p>
[QUOTE="Geeky1, post: 505769, member: 34442"] It's conceivable that it could be a software issue, but to be honest I think it's highly unlikely, because memtest/rember would have to interfere with the CPU diode measurement in some way, and I've never seen a program do that. I've seen Motherboard Monitor (old PC hardware monitoring program) return implausible-sometimes impossible-values for temperatures, but only when the wrong board or sensor configuration was selected. I'm not saying it's impossible that it's a software glitch, but I really feel that it's unlikely. If anything was going to cause weird temperature readings, it'd be running more than one hardware monitoring program at a time, which would create a potential for both programs to try to access the same sensor at the same time, that could then cause bogus readings. But my temperatures are the same regardless of whether Hardware Monitor or SMC Fan Control are running alone, or both are running together. I can't prove it conclusively, but I really, really, REALLY don't think this is a software problem. It just doesn't add up for me. It's possible for a CPU to experience localized heating where one part of the die is significantly hotter than another. This is particularly true when the CPU has very, very poor contact with the heatsink base (as it seems to in many MBPs). And, though I'm not an electrical engineer by any means, from what I've been given to understand Intel (and AMD) tends to put the on-die temperature diode in whatever area of the cpu will get the hottest (that'd be the logical place to put it). Which means that while I suppose that there's a chance that it's a software glitch (though I can't fathom how), my gut feeling is that it's more likely that the reading is accurate. Why? A couple reasons... [LIST=1] [*]The MBP's fans will not necessarily speed up significantly with increased CPU load, meaning that it's not an accurate indicator of how hot the CPU is getting in all cases. As I mentioned, the sensors that control the fan speed appear to sense the heatpipe temperature, not the CPU temperature; this is supported by the fact that people have reported their fans running at full speed constantly if the thermistors on the heatpipe are not reconnected after disassembling the machine. Unfortunately, the thermistors on the heatpipes register temperatures much lower than the actual CPU/GPU/NB temperatures, likely thanks to poor contact between the CPU and the heatsink, thus the fans can sit at 2500rpms or whatever while the CPU cooks merrily away at 90*C. [*]The MBP has a known heat issue that, by all accounts, is traceable to an issue with the thermal interface between the CPU and the heatsink (and the amount of thermal grease Apple puts on these things is further evidence of a contact problem). Fullscreening the visualizer in iTunes will run both my current one and the one I had to exchange up past 90*C, and my grandmother's behaves similarly. Memtest is very, very hard on certain parts of the CPU, and this, combined with the thermal interface problem, could very well result in localized areas of the CPU die topping 100*C. [/LIST] Ideally, someone with Windows XP installed on their MBP (I'm still trying to find any one of my XP CDs :() would download and run the Intel Thermal Analysis Tool and report how hot the CPU gets when the TAT is set to run both cores at 100% load. That program will produce more heat from the CPU than anything else I've come across-that's what Intel designed it to do. Supposedly (though I have no way of confirming it) it will make the processor dissipate at LEAST its TDP, if not slightly more. That'd give us an idea, I think, of how hot the CPU will get, realistically speaking. It'd be even better if they scanned for artifacts in ATItool or ran rthdribl at the same time, as those programs will push the GPU pretty hard, and since the GPU and the CPU share a common heatsink... I'd be interested to see if that would generate results similar to Rember or not. [/QUOTE]
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Rember on the MBP-Or, "how to cook an Apple"
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