I was using this command to read the temperature of cpu:

cat /sys/class/thermal/thermal_zone0/temp

Then I was looking for some other options and suddenly found that there is another option to find out core temperature. Since this CPU has two cores I am seeing temperature range of

thermal_zone0 - 45-50 D C

Core 0 - 60- 95 D C

Core 1 - 60 - 95 D C

It is near about boiling point of water. Is it okay to have this kind of temperature spike or should I change my cooler to something better?

  • 1
    FWIW I disagree with the downvotes and assert this is exactly the kind of question Superuser.com is for - and the number of questions associated with the applied tags evidence this.
    – davidgo
    Jul 31, 2020 at 7:46

3 Answers 3


It is impossible to say for sure without knowing what the CPU was doing at the time (and relatedly what speed it was clocked at).

That CPU is very old (released in 2008) and has a 65 watt TDP - so that it can generate this kind of heat is not a surprise or necessarily a problem. It may comfort/help you to know that Intel CPUs have logic in them to slow the CPUs down when they are very hot so they don't get damaged.

That said, as per the link above, the TCASE for this processor is 72.4 degrees C (TCASE being "Case Temperature is the maximum temperature allowed at the processor Integrated Heat Spreader (IHS).") - so assuming thermal_zone0 is measuring this - which I expect it is - the CPU is operating well within spec.

I would comment that except for unusual use cases, spending any money on that system (eg to replace the cooler) is throwing good money after bad. That system is passed its use-by date, and if its getting a significant level of use its probably costing $50-$100 per year in power - so you could probably pick up a 4-6 year old PC/laptop and, over a period of 3-5 years be better off financially - and have a faster and more reliable system. (Intel spent lots of effort making their CPUs a LOT more power efficient in between very roughly 2012 and 2016)


As mentioned by davidgo, it's impossible to know if those temperatures are "normal" without knowing what you were doing when the CPU cores were at 95°C (and what OS you're using). The CPU being old and having a TDP of 65W are also good points. I wouldn't recommend spending much money on any cooling solutions, but I would recommend trying to lower your temperatures in some other ways.

I wouldn't exactly say 95°C is "well within spec". Seems like 95°C is also within specs - apparently max core temps for E8400 are around 100°C. More interesting info on core temps (Tjunction) on Tom's Hardware.

I've written an answer here for this question at AskUbuntu which might help you: How to decrease overall temperature?

  • 95 degrees is in the core. The temperature if relevance is the tCASE which is well within spec.
    – davidgo
    Jul 31, 2020 at 8:48
  • Updated my answer - I know you were refering to Tcase temp which is below 73°C, however I was talking specifically about core temps - which are in fact still within specification (but definitely at the top end of it).
    – GChuf
    Jul 31, 2020 at 9:08

I have a similar CPU in a clunky old Core2 machine (E6600, first gen core2, even older than yours) and I think Linux reads its CPU temp as 20 degrees(?) higher than it actually is.

Or else the first couple years I had it, Linux was reading it 20 degrees too low?

Anyway, I wouldn't 100% trust those numbers if that's at idle. But I forget the details, if I ever got to the bottom of this change that I think happened at some point, so I don't know if that's real or not.

sensors on my Core2 system says:

Adapter: PCI adapter
temp1:        +50.5°C  (crit = +120.0°C, hyst = +90.0°C)

Adapter: ISA adapter
Core 0:       +72.0°C  (high = +86.0°C, crit = +100.0°C)
Core 1:       +71.0°C  (high = +86.0°C, crit = +100.0°C)

This seems unreasonably high; the thermal resistance between the silicon and the heat-sink isn't huge, and touching the heat sink even near the base doesn't feel that hot.

By comparison, modern CPUs run much cooler, e.g. my Skylake i7-6700k is idling at ~33C, just a few degrees above ambient. (It's a fairly hot day, like 27C or so.)

Both systems have fairly large 3rd-party CPU coolers, but the Skylake system runs cool enough that I can configure the BIOS to let the case fans spin all the way down to stopping when the CPU / mobo temps are below 45C or something, I forget exactly what I set.

As other answers have pointed out, much of the improvement to x86 microarchitectures in recent years has been to make them more power efficient, allowing higher clock speeds without melting, but also improving idle / low-load power dramatically. (The laptop market is important, and Intel and AMD both use the same basic design of a core in their laptop, desktop, and server chips.)

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