CPU core temperature high and cycling using stress

My new build Ubuntu PC seems to have high temperature cycling (and fan speed cycling) when testing using stress -c 4 - load up 4 cores. stress does load up to 100% but the temp and fans then start cycling a bit...

Higher resolution: CPU Fan on 100% set in bios: and here, again 100% CPU fan, not always so neat cycles:

Has anyone noticed similar characteristics?

Is this indicative of a problem? - poor heatsink compound connection?

Or should I be looking at the 'average' temperature which I visually estimate about 75-80deg ?

I have tried setting the fan thresholds in bios but still see same thing.

Thanks

xc

My setup:

• All new, no dust, ambient ~26-28deg
• i7 6700K - no OC (no plan to either)
• Z170 board
• Cooler Master Hyper 103 CPU fan (running ~50-100% speed - not 0 as in the graph)
• 2 intake and 1 exhaust case fan

sensors gives (a few secs of ~6X deg and a few secs of ~8X deg):

$ sensors
acpitz-virtual-0
Adapter: Virtual device
temp1:        +27.8°C  (crit = +119.0°C)
temp2:        +29.8°C  (crit = +119.0°C)

coretemp-isa-0000
Adapter: ISA adapter
Physical id 0:  +65.0°C  (high = +80.0°C, crit = +100.0°C)
Core 0:         +65.0°C  (high = +80.0°C, crit = +100.0°C)
Core 1:         +64.0°C  (high = +80.0°C, crit = +100.0°C)
Core 2:         +63.0°C  (high = +80.0°C, crit = +100.0°C)
Core 3:         +62.0°C  (high = +80.0°C, crit = +100.0°C)

asus-isa-0000
Adapter: ISA adapter
cpu_fan:        0 RPM

$ sensors
acpitz-virtual-0
Adapter: Virtual device
temp1:        +27.8°C  (crit = +119.0°C)
temp2:        +29.8°C  (crit = +119.0°C)

coretemp-isa-0000
Adapter: ISA adapter
Physical id 0:  +86.0°C  (high = +80.0°C, crit = +100.0°C)
Core 0:         +86.0°C  (high = +80.0°C, crit = +100.0°C)
Core 1:         +81.0°C  (high = +80.0°C, crit = +100.0°C)
Core 2:         +81.0°C  (high = +80.0°C, crit = +100.0°C)
Core 3:         +80.0°C  (high = +80.0°C, crit = +100.0°C)

asus-isa-0000
Adapter: ISA adapter
cpu_fan:        0 RPM

$ sensors
acpitz-virtual-0
Adapter: Virtual device
temp1:        +27.8°C  (crit = +119.0°C)
temp2:        +29.8°C  (crit = +119.0°C)

coretemp-isa-0000
Adapter: ISA adapter
Physical id 0:  +86.0°C  (high = +80.0°C, crit = +100.0°C)
Core 0:         +86.0°C  (high = +80.0°C, crit = +100.0°C)
Core 1:         +81.0°C  (high = +80.0°C, crit = +100.0°C)
Core 2:         +81.0°C  (high = +80.0°C, crit = +100.0°C)
Core 3:         +80.0°C  (high = +80.0°C, crit = +100.0°C)

asus-isa-0000
Adapter: ISA adapter
cpu_fan:        0 RPM

$ sensors
acpitz-virtual-0
Adapter: Virtual device
temp1:        +27.8°C  (crit = +119.0°C)
temp2:        +29.8°C  (crit = +119.0°C)

coretemp-isa-0000
Adapter: ISA adapter
Physical id 0:  +87.0°C  (high = +80.0°C, crit = +100.0°C)
Core 0:         +87.0°C  (high = +80.0°C, crit = +100.0°C)
Core 1:         +83.0°C  (high = +80.0°C, crit = +100.0°C)
Core 2:         +81.0°C  (high = +80.0°C, crit = +100.0°C)
Core 3:         +80.0°C  (high = +80.0°C, crit = +100.0°C)

asus-isa-0000
Adapter: ISA adapter
cpu_fan:        0 RPM

$ sensors
acpitz-virtual-0
Adapter: Virtual device
temp1:        +27.8°C  (crit = +119.0°C)
temp2:        +29.8°C  (crit = +119.0°C)

coretemp-isa-0000
Adapter: ISA adapter
Physical id 0:  +87.0°C  (high = +80.0°C, crit = +100.0°C)
Core 0:         +87.0°C  (high = +80.0°C, crit = +100.0°C)
Core 1:         +83.0°C  (high = +80.0°C, crit = +100.0°C)
Core 2:         +81.0°C  (high = +80.0°C, crit = +100.0°C)
Core 3:         +80.0°C  (high = +80.0°C, crit = +100.0°C)

asus-isa-0000
Adapter: ISA adapter
cpu_fan:        0 RPM

$ sensors
acpitz-virtual-0
Adapter: Virtual device
temp1:        +27.8°C  (crit = +119.0°C)
temp2:        +29.8°C  (crit = +119.0°C)

coretemp-isa-0000
Adapter: ISA adapter
Physical id 0:  +66.0°C  (high = +80.0°C, crit = +100.0°C)
Core 0:         +66.0°C  (high = +80.0°C, crit = +100.0°C)
Core 1:         +64.0°C  (high = +80.0°C, crit = +100.0°C)
Core 2:         +64.0°C  (high = +80.0°C, crit = +100.0°C)
Core 3:         +64.0°C  (high = +80.0°C, crit = +100.0°C)

asus-isa-0000
Adapter: ISA adapter
cpu_fan:        0 RPM

Recent Questions...