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i7 8700 High Package TDP and High Temps (when running fans at 100%)

I recently purchased an i7 8700 and a Cryorig H7 thinking that with a listed TDP of 65W on intel's specsheet and with the cooler's highest heat dissipation of 140W I should be more than fine. However, I stress tested the CPU in Prime 95 and noticed that it's temps jumped up near 100 degrees celsius and its package TDP in intel's extreme tuning software was shown as 195W. Is this normal for this processor? Is it behaving weirdly? Should I take notice of the temps I'm getting or are they likely to just be ridiculously high for my intended use case for this processor (i.e. playing modern games and a bit of CAD)?

EDIT: I just though that I should add that it idles at about 35 - 40c, goes up to about 60C in games, goes up to 77/78C in Intel Extreme Utility and as I said before runs up to 100C in Prime 95 (with my CPU cooler fans at their full speed).
Reply to Pezza349
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  1. Which version of Prime95?
    Reply to CompuTronix
  2. CompuTronix said:
    Which version of Prime95?

    I was running version 29.4b7. I was also running all 12 threads in the "Maximum Heat" mode.
    Reply to Pezza349
  3. Best answer
    Pezza349.

    Do not run any versions of Prime95 later than 26.6. Here's why:

    Intel tests their processors at a steady100% TDP workload. Prime95 version 26.6 Small FFT's is ideal for CPU thermal testing, because it's a steady 100% workload with steady Core temperatures that typically runs Core i variants with Hyperthreading and Core 2 processors within +/- a few % of TDP. No other utility so closely replicates Intel's proprietary test conditions. This is also the utility that Real Temp uses to test Core temperature sensors.

    100% CPU Utilization in Windows Task Manager seldom equals 100% workload or TDP. When performing a thermal test, the objective is to run utilities that won't overload or underload you processor. Here’s a sample of utilities grouped as thermal and stability tests according to % of TDP, averaged across five Generations of processors at stock settings:

    TDP ... Thermal Test - Steady Workload

    129% ... Prime95 v27.7 through v29.4 - Small FFT’s (AVX, No Offset)
    101% <-- Prime95 v26.6 - Small FFT’s
    89% ... HeavyLoad v3.4.0.234 - Stress CPU
    87% ... FurMark v1.19.1.0 - CPU Burner
    78% ... CPU-Z v1.82.0 - Bench - Stress CPU
    66% ... AIDA64 v5.95.4500 - System Stability Test - Stress CPU

    TDP ... Stability Test - Fluctuating Workload (Peak)

    123% ... OCCT v4.5.1 - CPU: OCCT (AVX, No Offset)
    118% ... LinX v0.6.5 - Default
    116% ... IntelBurn Test v2.54 - High
    113% ... OCCT v4.5.1 - CPU: Linpack (AVX, No Offset)
    110% ... AIDA64 v5.95.4500 - System Stability Test - Stress FPU
    99% <-- Asus RealBench v2.56 - Stress Test (AVX, No Offset)
    97% ... Intel Processor Diagnostic Tool v4.1.0.24 - Default
    94% ... Sandra 2017.09.24.41 - Burn in - Processor Tests
    92% ... CineBench v15.0 - CPU - Render Test
    79% ... Intel Extreme Tuning Utility v6.4.1.15 - CPU Stress Test

    All tests will show 100% CPU Utilization in Windows Task Manager, regardless of actual Workload. Higher TDP tests produce higher Core temperatures. Power (Watts) and Core temperatures will vary with Microarchitecture, Core count, Core speed, Core voltage, VID, Turbo Boost, Hyperthreading, Instruction Sets, Memory, IGPU, CPU cooler, BIOS versions and Microcode.

    2nd through 8th Generation i3, i5 and i7 CPU's have AVX (Advanced Vector Extension) Instruction Sets. Prime95 versions later than 26.6 run AVX code on the CPU's Floating Point Unit (FPU) which causes unrealistic temperatures up to 20°C higher due to excessively high TDP workloads, as shown above. Other high TDP utilities have similar results.

    AVX can be disabled in Prime95 versions later than 26.6 by inserting "CpuSupportsAVX=0" into the "local.txt" file in Prime95's folder. However, since Core temperatures will be the same as 26.6, it's easier to just use 26.6. AVX doesn't affect Core i 1st Generation, Core 2, Pentium or Celeron processors since they don't have AVX Instruction Sets.

    • Download Prime95 version 26.6 - http://www.mersenneforum.org/showthread.php?t=15504

    Run only Small FFT's for just 10 minutes.

    Your Core temperatures will be up to 20°C lower. Give it a try.

    This is what it looks like:

    http://imgur.com/AV0iCxD.jpgShown above from left to right: Small FFT's, Blend, Linpack and Intel Burn Test.

    Note the steady thermal signature of Small FFT's, which allows accurate measurements of Core temperatures. A steady 100% workload is crucial for thermal testing so the CPU, cooler, socket, motherboard and voltage regulators can thermally stabilize.

    Also, if you'd like to get yourself up to speed on this topic, then read our Sticky: Intel Temperature Guide - http://www.tomshardware.com/forum/id-1800828/intel-temperature-guide.html

    CT :sol:
    Reply to CompuTronix
  4. CompuTronix said:
    Pezza349.

    Do not run any versions of Prime95 later than 26.6. Here's why:

    Intel tests their processors at a steady100% TDP workload. Prime95 version 26.6 Small FFT's is ideal for CPU thermal testing, because it's a steady 100% workload with steady Core temperatures that typically runs Core i variants with Hyperthreading and Core 2 processors within +/- a few % of TDP. No other utility so closely replicates Intel's proprietary test conditions. This is also the utility that Real Temp uses to test Core temperature sensors.

    100% CPU Utilization in Windows Task Manager seldom equals 100% workload or TDP. When performing a thermal test, the objective is to run utilities that won't overload or underload you processor. Here’s a sample of utilities grouped as thermal and stability tests according to % of TDP, averaged across five Generations of processors at stock settings:

    TDP ... Thermal Test - Steady Workload

    129% ... Prime95 v27.7 through v29.4 - Small FFT’s (AVX, No Offset)
    101% <-- Prime95 v26.6 - Small FFT’s
    89% ... HeavyLoad v3.4.0.234 - Stress CPU
    87% ... FurMark v1.19.1.0 - CPU Burner
    78% ... CPU-Z v1.82.0 - Bench - Stress CPU
    66% ... AIDA64 v5.95.4500 - System Stability Test - Stress CPU

    TDP ... Stability Test - Fluctuating Workload (Peak)

    123% ... OCCT v4.5.1 - CPU: OCCT (AVX, No Offset)
    118% ... LinX v0.6.5 - Default
    116% ... IntelBurn Test v2.54 - High
    113% ... OCCT v4.5.1 - CPU: Linpack (AVX, No Offset)
    110% ... AIDA64 v5.95.4500 - System Stability Test - Stress FPU
    99% <-- Asus RealBench v2.56 - Stress Test (AVX, No Offset)
    97% ... Intel Processor Diagnostic Tool v4.1.0.24 - Default
    94% ... Sandra 2017.09.24.41 - Burn in - Processor Tests
    92% ... CineBench v15.0 - CPU - Render Test
    79% ... Intel Extreme Tuning Utility v6.4.1.15 - CPU Stress Test

    All tests will show 100% CPU Utilization in Windows Task Manager, regardless of actual Workload. Higher TDP tests produce higher Core temperatures. Power (Watts) and Core temperatures will vary with Microarchitecture, Core count, Core speed, Core voltage, VID, Turbo Boost, Hyperthreading, Instruction Sets, Memory, IGPU, CPU cooler, BIOS versions and Microcode.

    2nd through 8th Generation i3, i5 and i7 CPU's have AVX (Advanced Vector Extension) Instruction Sets. Prime95 versions later than 26.6 run AVX code on the CPU's Floating Point Unit (FPU) which causes unrealistic temperatures up to 20°C higher due to excessively high TDP workloads, as shown above. Other high TDP utilities have similar results.

    AVX can be disabled in Prime95 versions later than 26.6 by inserting "CpuSupportsAVX=0" into the "local.txt" file in Prime95's folder. However, since Core temperatures will be the same as 26.6, it's easier to just use 26.6. AVX doesn't affect Core i 1st Generation, Core 2, Pentium or Celeron processors since they don't have AVX Instruction Sets.

    • Download Prime95 version 26.6 - http://www.mersenneforum.org/showthread.php?t=15504

    Run only Small FFT's for just 10 minutes.

    Your Core temperatures will be up to 20°C lower. Give it a try.

    This is what it looks like:

    http://imgur.com/AV0iCxD.jpgShown above from left to right: Small FFT's, Blend, Linpack and Intel Burn Test.

    Note the steady thermal signature of Small FFT's, which allows accurate measurements of Core temperatures. A steady 100% workload is crucial for thermal testing so the CPU, cooler, socket, motherboard and voltage regulators can thermally stabilize.

    Also, if you'd like to get yourself up to speed on this topic, then read our Sticky: Intel Temperature Guide - http://www.tomshardware.com/forum/id-1800828/intel-temperature-guide.html

    CT :sol:


    Thank you so much for your help, I was really freaking out for a second but thanks to your quick response it looks like the processor is running much cooler. It after about 3 - 4 minutes it peaked at 85C and stayed at that temperature for the rest of the stress test. Is this a safe max operating temp or is it a bit too hot in your opinion. I know that in the link you left in your response that it said that 85C is too hot but I was just wondering why this is the case seeing as this temperature is the worst case scenario and it's still 15C below the maximum recommended temperature by Intel of 100C.
    Reply to Pezza349
  5. Pezza349 said:
    ... peaked at 85C ... Is this a safe max operating temp ... the link you left in your response that it said that 85C is too hot but I was just wondering why this is the case seeing as this temperature is the worst case scenario and it's still 15C below the maximum recommended temperature by Intel of 100C.
    Pezza349.

    The Intel Temperature Guide actually says:

    " ... Core temperatures above 85°C aren't recommended.

    Core temperatures below 80°C are preferred.

    http://imgur.com/Svr2si8.jpgCore temperatures increase and decrease with Ambient temperature. ... "

    It also says:

    " ... Although most processors Throttle at 100°C (212°F) ... it’s not advisable to run your CPU near it's thermal limit, just as common sense tells you not to run a vehicle with the temperature gauge pegged in the red "hot" zone.

    If your hottest Core is near it’s specified Tj Max Throttle temperature, then your CPU is already too hot. The consensus among well informed and highly experienced system builders, overclockers and reviewers, is that cooler is better for ultimate stability, performance and longevity. Experts all agree that it's prudent to observe a reasonable thermal margin below Tj Max. So regardless of environmental conditions, hardware configurations, workloads or any other variables, Core temperatures above 85°C aren't recommended. ... "

    Accordingly, you need to leave thermal headroom to accommodate the potential for running very heavy workloads, as well as an increase in seasonal ambient temperature.

    Q What is your ambient (room) temperature?

    If it's winter where you live, then your ambient temperature is most likely a few degrees below "standard" or normal, which is 22°C or 72°F. Since Core temperatures increase and decrease with ambient temperature, when the season changes to summer, your ambient temperature will likely be at least a few degrees above normal. This means your Core temperatures will increase just as much as your ambient temperature.

    CT :sol:
    Reply to CompuTronix
  6. CompuTronix said:
    Pezza349 said:
    ... peaked at 85C ... Is this a safe max operating temp ... the link you left in your response that it said that 85C is too hot but I was just wondering why this is the case seeing as this temperature is the worst case scenario and it's still 15C below the maximum recommended temperature by Intel of 100C.
    Pezza349.

    The Intel Temperature Guide actually says:

    " ... Core temperatures above 85°C aren't recommended.

    Core temperatures below 80°C are preferred.

    http://imgur.com/Svr2si8.jpgCore temperatures increase and decrease with Ambient temperature. ... "

    It also says:

    " ... Although most processors Throttle at 100°C (212°F) ... it’s not advisable to run your CPU near it's thermal limit, just as common sense tells you not to run a vehicle with the temperature gauge pegged in the red "hot" zone.

    If your hottest Core is near it’s specified Tj Max Throttle temperature, then your CPU is already too hot. The consensus among well informed and highly experienced system builders, overclockers and reviewers, is that cooler is better for ultimate stability, performance and longevity. Experts all agree that it's prudent to observe a reasonable thermal margin below Tj Max. So regardless of environmental conditions, hardware configurations, workloads or any other variables, Core temperatures above 85°C aren't recommended. ... "

    Accordingly, you need to leave thermal headroom to accommodate the potential for running very heavy workloads, as well as an increase in seasonal ambient temperature.

    Q What is your ambient (room) temperature?

    If it's winter where you live, then your ambient temperature is most likely a few degrees below "standard" or normal, which is 22°C or 72°F. Since Core temperatures increase and decrease with ambient temperature, when the season changes to summer, your ambient temperature will likely be at least a few degrees above normal. This means your Core temperatures will increase just as much as your ambient temperature.

    CT :sol:


    Thank you for your reply. I think I've solved the issue now. I undervolted my CPU to a stable level (1.14V) and it's still able to run at its max clocks on all cores with a maximum temperature (after two hours of Prime 95) of 77C. Thank you for all of your advice for my issue it really helped me to finally arrive at a solution.
    Reply to Pezza349
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