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What is likely cause of overheating CPU
This is a continuation of the thread "Freeze-ups. Is power supply the
only remaining possibility?" At this point I'm seriously considering replacing either the motherboard or the CPU or both. To summarize: I acqired this computer with an unknown problem. The symptoms began with persistent and almost immediate system freezes. This would happen with any sort of high level activity, for example installing Windows or runnning Windows. The motherboard had 2 visibly damaged capacitors which I replaced. This made a major improvement, to the extent that I thought it was "fixed". I later replaced the third cap in that cluster. The freezes returned but now usually take several hours to occur. I didn't start monitoring the CPU temperature until after these freezes. The reported CPU temp is consistently 30-40C in BIOS setup and 69-72C in Windows. I was skeptical of these numbers but I think they may be accurate. I ran for several minutes with the CPU fan unplugged and the temp slowly rose from 70 to 92C. During that time the CPU was seen to throttle back to about 56%. I also (with the fan running) aimed a hair dryer at the heatsink and saw the temp rise from 70-74C with the fan increasing rpm from the usual 3000 to 4500. I stopped the hair dryer and the temp dropped to 70 with the fan coming back to 3000 rpm. I have also replaced the heatsink/fan. So, if something is causing the freezes and perhaps as a side effect is also causing the overheating, would that fault likely lie with the CPU or on some component of the motherboard? I have tested the power supply with a multimeter while the computer is under heavy load and the voltages are well within tolerance. I have swapped out the RAM and hard drives. No hardware conflicts reported in Device Manager, nothing obvious in Event Logs, although I'm honestly not sure what to look for. System: Asrock M266A motherboard Celeron 2.4 512 MB DDR Thanks, Graham |
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#2 |
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Guest
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Re: What is likely cause of overheating CPU
Graham wrote:
> This is a continuation of the thread "Freeze-ups. Is power supply the > only remaining possibility?" > > At this point I'm seriously considering replacing either the > motherboard or the CPU or both. > > To summarize: > > I acqired this computer with an unknown problem. The symptoms began > with persistent and almost immediate system freezes. This would happen > with any sort of high level activity, for example installing Windows > or runnning Windows. The motherboard had 2 visibly damaged capacitors > which I replaced. This made a major improvement, to the extent that I > thought it was "fixed". I later replaced the third cap in that > cluster. > > The freezes returned but now usually take several hours to occur. I > didn't start monitoring the CPU temperature until after these freezes. > The reported CPU temp is consistently 30-40C in BIOS setup and 69-72C > in Windows. I was skeptical of these numbers but I think they may be > accurate. I ran for several minutes with the CPU fan unplugged and the > temp slowly rose from 70 to 92C. During that time the CPU was seen to > throttle back to about 56%. I also (with the fan running) aimed a hair > dryer at the heatsink and saw the temp rise from 70-74C with the fan > increasing rpm from the usual 3000 to 4500. I stopped the hair dryer > and the temp dropped to 70 with the fan coming back to 3000 rpm. > > I have also replaced the heatsink/fan. > > So, if something is causing the freezes and perhaps as a side effect > is also causing the overheating, would that fault likely lie with the > CPU or on some component of the motherboard? > > I have tested the power supply with a multimeter while the computer is > under heavy load and the voltages are well within tolerance. I have > swapped out the RAM and hard drives. > > No hardware conflicts reported in Device Manager, nothing obvious in > Event Logs, although I'm honestly not sure what to look for. > > System: > Asrock M266A motherboard > Celeron 2.4 > 512 MB DDR > > Thanks, > Graham Flip to page 24 of this document. See Figure 4. http://download.intel.com/support/pr...b/25174807.pdf Your processor has a nominal Vcore of around 1.5V. It could be 1.475, 1.5, or 1.525V. This was typical for the 0.13 micron processors (like my Tualatin S370). Figure 4 is a "load line". When the processor is not busy, it doesn't draw much current. The operating point would be on the left hand side of the plot, on one of those lines. When the processor is running Orthos or CPUBurn, it is somewhere closer to the right hand side. As the current drawn goes up, the Vcore becomes reduced in value, or "droops". According the the lines, when the current drawn is zero, the processor is not supposed to be operating at the specified VID of 1.5V. The processor is supposed to be run at a little less voltage. And, in fact, since the current does not drop to zero, you are actually a small distance from the left of the graph, so the idle Vcore should be less than 1.5V. You mentioned 1.6V, and if that was measured at idle, that is too high to fit within the bounds of the upper and lower lines. Your processor might draw 50 amps under load, in which case the Vcore value drops by 0.135V below nominal. So, instead of seeing 1.5V, you'd see 1.365V or so. So it is important to note the conditions, during which the Vcore was measured. It is either close to normal (if measured at idle), or grossly off, if it was measured under load. I agree, that either your processor or your motherboard is at fault. But the processor managed to pass several hours of Orthos, which means it is not such a bad character after all. I'd check out what is going on with the Vcore voltage, as you vary the load conditions, and see if the voltage is grossly out of whack. In which case, you might want to replace the motherboard. If I didn't know which was busted, I'd have to start with the motherboard, due to the excellent record I've personally witnessed over the years, regarding defective processors. So if the Vcore remains too high, and there is no BIOS adjustment to try dropping it, then changing the motherboard is what I'd do next. Paul |
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#3 |
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Re: What is likely cause of overheating CPU
On Mon, 15 Oct 2007 01:56:21 -0400, Paul <nospam@needed.com> wrote:
> >Your processor might draw 50 amps under load, in which case the Vcore value >drops by 0.135V below nominal. So, instead of seeing 1.5V, you'd see 1.365V >or so. > >So it is important to note the conditions, during which the Vcore was measured. >It is either close to normal (if measured at idle), or grossly off, if it was >measured under load. Thanks again, Paul. Under load, the lowest I've seen is 1.52V, mostly about 1.6, as high as 1.66. This is as reported by software. I don't think I'm capable of getting a multimeter reading of VCore. Given that the software readings I'm getting for 3.3V, 5V and 12V are showing somewhat lower than my multimeter says, should I trust the VCore voltage readings and conclude that VCore is really running high? Graham |
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#4 |
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Re: What is likely cause of overheating CPU
Not Here wrote:
> On Mon, 15 Oct 2007 01:56:21 -0400, Paul <nospam@needed.com> wrote: > > >> Your processor might draw 50 amps under load, in which case the Vcore value >> drops by 0.135V below nominal. So, instead of seeing 1.5V, you'd see 1.365V >> or so. >> >> So it is important to note the conditions, during which the Vcore was measured. >> It is either close to normal (if measured at idle), or grossly off, if it was >> measured under load. > > Thanks again, Paul. > > Under load, the lowest I've seen is 1.52V, mostly about 1.6, as high > as 1.66. This is as reported by software. I don't think I'm capable of > getting a multimeter reading of VCore. > > Given that the software readings I'm getting for 3.3V, 5V and 12V are > showing somewhat lower than my multimeter says, should I trust the > VCore voltage readings and conclude that VCore is really running high? > > Graham > I'd say it is probably on the high side. But it is hard to believe that would drive the temperature up that much. Paul |
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#5 |
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Re: What is likely cause of overheating CPU
On Oct 15, 2:27 am, Not Here <noth...@notnow.com> wrote:
> Given that the software readings I'm getting for 3.3V, 5V and 12V are > showing somewhat lower than my multimeter says, should I trust the > VCore voltage readings and conclude that VCore is really running high? Because of a voltage monitor may be designed, CPU voltage numbers may be more accurate. Of course it is easy to verify those numbers once the difficult part is accomplished - tracing those voltage lines back from CPU pins. Meanwhile I still don't see where useful experiments were performed. For example, as CPU is heated significantly with a hairdryer on highest heat (or something even warmer), then what happens to reported CPU temperatures? That temperature rise should be apparent is less than a minute - or faster. After put into a condition where problems can be located (motherboard et al heated as hot as the hairdryer can take it), then what did diagnostics report? Your previous tests were not definitive because standard extremes were not implemented. Minor voltage changes on CPU would have zero effect on CPU temperature. But voltage variation can affect timing. Heat is a diagnostic tool. Too often, heat is blamed for failures when the human does not understand semiconductor and computer principles. Some are so misinformed as to assume those higher temperatures create hardware damage. Heat is a diagnostic tool. |
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#6 |
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Re: What is likely cause of overheating CPU
On Fri, 19 Oct 2007 17:13:47 -0700, w_tom <w_tom1@usa.net> wrote:
>On Oct 15, 2:27 am, Not Here <noth...@notnow.com> wrote: >> Given that the software readings I'm getting for 3.3V, 5V and 12V are >> showing somewhat lower than my multimeter says, should I trust the >> VCore voltage readings and conclude that VCore is really running high? > > Because of a voltage monitor may be designed, CPU voltage numbers >may be more accurate. Of course it is easy to verify those numbers >once the difficult part is accomplished - tracing those voltage lines >back from CPU pins. > > Meanwhile I still don't see where useful experiments were >performed. For example, as CPU is heated significantly with a >hairdryer on highest heat (or something even warmer), then what >happens to reported CPU temperatures? That temperature rise should be >apparent is less than a minute - or faster. > > After put into a condition where problems can be located >(motherboard et al heated as hot as the hairdryer can take it), then >what did diagnostics report? Your previous tests were not definitive >because standard extremes were not implemented. > > Minor voltage changes on CPU would have zero effect on CPU >temperature. But voltage variation can affect timing. > > Heat is a diagnostic tool. Too often, heat is blamed for failures >when the human does not understand semiconductor and computer >principles. Some are so misinformed as to assume those higher >temperatures create hardware damage. Heat is a diagnostic tool. The reported CPU temp is consistently 30-40C in BIOS setup and 69-72C in Windows. I was skeptical of these numbers but I think they may be accurate. I ran for several minutes with the CPU fan unplugged and the temp slowly rose from 70 to 92C. During that time the CPU was seen to throttle back to about 56%. I also (with the fan running) aimed a hair dryer at the heatsink and saw the temp rise from 70-74C with the fan increasing rpm from the usual 3000 to 4500. I stopped the hair dryer and the temp dropped to 70 with the fan coming back to 3000 rpm. I have also replaced the heatsink/fan. What diagnostics would you recommend I do while the system is being overheated? Graham |
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#7 |
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Re: What is likely cause of overheating CPU
On Oct 14, 10:37 pm, Graham <noth...@notnow.com> wrote:
> This is a continuation of the thread "Freeze-ups. Is power supply the > only remaining possibility?" > > At this point I'm seriously considering replacing either the > motherboard or the CPU or both. > > To summarize: > > I acqired this computer with an unknown problem. The symptoms began > with persistent and almost immediate system freezes. This would happen > with any sort of high level activity, for example installing Windows > or runnning Windows. The motherboard had 2 visibly damaged capacitors > which I replaced. This made a major improvement, to the extent that I > thought it was "fixed". I later replaced the third cap in that > cluster. > > The freezes returned but now usually take several hours to occur. I > didn't start monitoring the CPU temperature until after these freezes. > The reported CPU temp is consistently 30-40C in BIOS setup and 69-72C > in Windows. I was skeptical of these numbers but I think they may be > accurate. I ran for several minutes with the CPU fan unplugged and the > temp slowly rose from 70 to 92C. During that time the CPU was seen to > throttle back to about 56%. I also (with the fan running) aimed a hair > dryer at the heatsink and saw the temp rise from 70-74C with the fan > increasing rpm from the usual 3000 to 4500. I stopped the hair dryer > and the temp dropped to 70 with the fan coming back to 3000 rpm. > > I have also replaced the heatsink/fan. > > So, if something is causing the freezes and perhaps as a side effect > is also causing the overheating, would that fault likely lie with the > CPU or on some component of the motherboard? > > I have tested the power supply with a multimeter while the computer is > under heavy load and the voltages are well within tolerance. I have > swapped out the RAM and hard drives. > > No hardware conflicts reported in Device Manager, nothing obvious in > Event Logs, although I'm honestly not sure what to look for. > > System: > Asrock M266A motherboard > Celeron 2.4 > 512 MB DDR > > Thanks, > Graham IF i remember correctly, there are 4 green KZG capacitor at the west side of the board(next to mosfet), 4 brown KZE at the north side of the board. When replacing the caps at VRM, i will replace all . I will use panasonic FM since it has lowest esr(lower than FC, Chemicon KZE and KZG) I am just curious what cap you use. I have the same board before, the temp monitor is kind of off the scale. So i just use my finger to feel whether the mosfets and caps are hot or not when running prime95. The CPU voltage can be measured at the east side of the inductor(if i remember correctly, it is either the southest coil or middle one) The lowest voltage at the one of the inductor is the cpu voltage |
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#8 |
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Guest
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Re: What is likely cause of overheating CPU
On Oct 21, 12:16 am, Not Here <noth...@notnow.com> wrote:
> The reported CPU temp is consistently 30-40C in BIOS setup and 69-72C > in Windows. I was skeptical of these numbers but I think they may be > accurate. I ran for several minutes with the CPU fan unplugged and the > temp slowly rose from 70 to 92C. During that time the CPU was seen to > throttle back to about 56%. I also (with the fan running) aimed a hair > dryer at the heatsink and saw the temp rise from 70-74C with the fan > increasing rpm from the usual 3000 to 4500. I stopped the hair dryer > and the temp dropped to 70 with the fan coming back to 3000 rpm. > ... > What diagnostics would you recommend I do while the system is being > overheated? Temperature sensor does measure temperature change. If that number is also accurate, it is rather excessive (assuming this is not a CPU rated for 90 degree C). Only certain hardware can create an OS failure. Diagnostics, especially when hardware is heated, should be performed on video controller, sound card, memory, CPU, and motherboard hardware interfacing with those functions. Devices such as keyboard, mouse, floppy and hard drives, CD-Rom, etc would not cause a system freeze and need not be tested with diagnostics. If I understand (remember) what is (was) posted including CPU manufacturer, it does appear higher CPU temperature (created by hairdryer) is causing CPU to throttle. Minor changes in CPU voltages would not account for overheating. But minor CPU voltage changes can change CPU timings which (if large enough) could cause a CPU crash (freeze). However that temperature number for a CPU in room temperature (70 degree F) is troubling; may be too high depending on temp specs for that particular CPU. CPU heatsink - does the manufacturer provide a 'degree C per watt' spec? Suspicious is any heatsink assembly that does not provide that most fundamental number. Obviously, CPU performance should not be decreased by hairdryer heat. That is a suspicious and telling number. |
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#9 |
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Re: What is likely cause of overheating CPU
On Oct 24, 9:30 pm, saturn...@yahoo.com wrote:
> On Oct 14, 10:37 pm, Graham <noth...@notnow.com> wrote: > > > > > > > This is a continuation of the thread "Freeze-ups. Is power supply the > > only remaining possibility?" > > > At this point I'm seriously considering replacing either the > > motherboard or the CPU or both. > > > To summarize: > > > I acqired this computer with an unknown problem. The symptoms began > > with persistent and almost immediate system freezes. This would happen > > with any sort of high level activity, for example installing Windows > > or runnning Windows. The motherboard had 2 visibly damaged capacitors > > which I replaced. This made a major improvement, to the extent that I > > thought it was "fixed". I later replaced the third cap in that > > cluster. > > > The freezes returned but now usually take several hours to occur. I > > didn't start monitoring the CPU temperature until after these freezes. > > The reported CPU temp is consistently 30-40C in BIOS setup and 69-72C > > in Windows. I was skeptical of these numbers but I think they may be > > accurate. I ran for several minutes with the CPU fan unplugged and the > > temp slowly rose from 70 to 92C. During that time the CPU was seen to > > throttle back to about 56%. I also (with the fan running) aimed a hair > > dryer at the heatsink and saw the temp rise from 70-74C with the fan > > increasing rpm from the usual 3000 to 4500. I stopped the hair dryer > > and the temp dropped to 70 with the fan coming back to 3000 rpm. > > > I have also replaced the heatsink/fan. > > > So, if something is causing the freezes and perhaps as a side effect > > is also causing the overheating, would that fault likely lie with the > > CPU or on some component of the motherboard? > > > I have tested the power supply with a multimeter while the computer is > > under heavy load and the voltages are well within tolerance. I have > > swapped out the RAM and hard drives. > > > No hardware conflicts reported in Device Manager, nothing obvious in > > Event Logs, although I'm honestly not sure what to look for. > > > System: > > Asrock M266A motherboard > > Celeron 2.4 > > 512 MB DDR > > > Thanks, > > Graham > > IF i remember correctly, there are 4 green KZG capacitor at the west > side of the board(next to mosfet), 4 brown KZE at the north side of > the board. > When replacing the caps at VRM, i will replace all . I will use > panasonic FM since it has lowest esr(lower than FC, Chemicon KZE and > KZG) > I am just curious what cap you use. > I have the same board before, the temp monitor is kind of off the > scale. So i just use my finger to feel whether the mosfets and caps > are hot or not when running prime95. > The CPU voltage can be measured at the east side of the inductor(if i > remember correctly, it is either the southest coil or middle one) > The lowest voltage at the one of the inductor is the cpu voltage- Hide quoted text - > > - Show quoted text - KZG series caps sometimes have problems. They fail with no visible signs of a problem. I've repaired 4 motherboards (2 MSI, 1 Asus, 1 Gigabyte) by replacing only the KZG caps. It's not consistant and Chemicon isn't talking. Asrock is NOT Asus. (As some people seem to think.) Asrock is basically an Asus design that is physically manufactured by PcChips. (More correctly Hsing Tech who does the fabrication for PcChips and many other low end boards.) .. .. |
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#10 |
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Re: What is likely cause of overheating CPU
PCBONEZ@gmail.com wrote:
> On Oct 24, 9:30 pm, saturn...@yahoo.com wrote: >> On Oct 14, 10:37 pm, Graham <noth...@notnow.com> wrote: >> >> >> >> >> >>> This is a continuation of the thread "Freeze-ups. Is power supply the >>> only remaining possibility?" >>> At this point I'm seriously considering replacing either the >>> motherboard or the CPU or both. >>> To summarize: >>> I acqired this computer with an unknown problem. The symptoms began >>> with persistent and almost immediate system freezes. This would happen >>> with any sort of high level activity, for example installing Windows >>> or runnning Windows. The motherboard had 2 visibly damaged capacitors >>> which I replaced. This made a major improvement, to the extent that I >>> thought it was "fixed". I later replaced the third cap in that >>> cluster. >>> The freezes returned but now usually take several hours to occur. I >>> didn't start monitoring the CPU temperature until after these freezes. >>> The reported CPU temp is consistently 30-40C in BIOS setup and 69-72C >>> in Windows. I was skeptical of these numbers but I think they may be >>> accurate. I ran for several minutes with the CPU fan unplugged and the >>> temp slowly rose from 70 to 92C. During that time the CPU was seen to >>> throttle back to about 56%. I also (with the fan running) aimed a hair >>> dryer at the heatsink and saw the temp rise from 70-74C with the fan >>> increasing rpm from the usual 3000 to 4500. I stopped the hair dryer >>> and the temp dropped to 70 with the fan coming back to 3000 rpm. >>> I have also replaced the heatsink/fan. >>> So, if something is causing the freezes and perhaps as a side effect >>> is also causing the overheating, would that fault likely lie with the >>> CPU or on some component of the motherboard? >>> I have tested the power supply with a multimeter while the computer is >>> under heavy load and the voltages are well within tolerance. I have >>> swapped out the RAM and hard drives. >>> No hardware conflicts reported in Device Manager, nothing obvious in >>> Event Logs, although I'm honestly not sure what to look for. >>> System: >>> Asrock M266A motherboard >>> Celeron 2.4 >>> 512 MB DDR >>> Thanks, >>> Graham >> IF i remember correctly, there are 4 green KZG capacitor at the west >> side of the board(next to mosfet), 4 brown KZE at the north side of >> the board. >> When replacing the caps at VRM, i will replace all . I will use >> panasonic FM since it has lowest esr(lower than FC, Chemicon KZE and >> KZG) >> I am just curious what cap you use. >> I have the same board before, the temp monitor is kind of off the >> scale. So i just use my finger to feel whether the mosfets and caps >> are hot or not when running prime95. >> The CPU voltage can be measured at the east side of the inductor(if i >> remember correctly, it is either the southest coil or middle one) >> The lowest voltage at the one of the inductor is the cpu voltage- Hide quoted text - >> >> - Show quoted text - > > KZG series caps sometimes have problems. > They fail with no visible signs of a problem. > I've repaired 4 motherboards (2 MSI, 1 Asus, 1 Gigabyte) by replacing > only the KZG caps. > It's not consistant and Chemicon isn't talking. > > Asrock is NOT Asus. (As some people seem to think.) > Asrock is basically an Asus design that is physically manufactured by > PcChips. > (More correctly Hsing Tech who does the fabrication for PcChips and > many other low end boards.) > . > > . Are you sure? I thought Asrock was the budget arm of Asus. And ECS is PcChips. At least that's what I've always read and have been told. Bob |
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