NVIDIA Optimus: High CPU temperature with Fedora 27

I’m running Fedora 27 on a ThinkPad T530 with the NVIDIA Optimus enabled and my machine is running extremely hot after a while. The whole system starts to lag and the CPUs get throttled.

I guess this is related to the driver (nouveau) that is used for the NVIDIA card?

Is this a common problem? Would another driver help? Is there actually a linux driver from NVIDIA for this graphic card?

nouveau-pci-0100
Adapter: PCI adapter
GPU core:     +0.91 V  (min =  +0.84 V, max =  +1.09 V)
temp1:        +96.0°C  (high = +95.0°C, hyst =  +3.0°C)
                       (crit = +105.0°C, hyst =  +5.0°C)
                       (emerg = +135.0°C, hyst =  +5.0°C)

acpitz-virtual-0
Adapter: Virtual device
temp1:       +101.0°C  (crit = +103.0°C)

coretemp-isa-0000
Adapter: ISA adapter
Package id 0: +103.0°C  (high = +87.0°C, crit = +105.0°C)
Core 0:       +101.0°C  (high = +87.0°C, crit = +105.0°C)
Core 1:       +101.0°C  (high = +87.0°C, crit = +105.0°C)
Core 2:       +103.0°C  (high = +87.0°C, crit = +105.0°C)
Core 3:        +97.0°C  (high = +87.0°C, crit = +105.0°C)

thinkpad-isa-0000
Adapter: ISA adapter
fan1:        4274 RPM
Kernel: 4.14.6-300.fc27.x86_64
VGA compatible controller: Intel Corporation 3rd Gen Core processor Graphics Controller (rev 09)
	Subsystem: Lenovo Device 21f5
	Kernel driver in use: i915
VGA compatible controller: NVIDIA Corporation GF108M [NVS 5400M] (rev a1)
	Subsystem: Lenovo Device 21f5
	Kernel driver in use: nouveau

If both GPU and CPU are overheating, could this be a board issue? Maybe the board is overheating and heat is reaching the components.

Perhaps slightly, mostly in terms of performance tho. Chances are that nvidia card with opensource driver performs as badly as integrated gpu (and draws shitload more power -> generates heat).

Yes.

Anyways, arch wiki explains everything better than I could.

Not really, in vast majority of laptops GPU and CPU share single heat pipe, if you manage to overheat one of them it will negatively affect the other as well.

PS: Before looking anywhere else, considering that it is an older laptop, try to disassemble it and clean chunks of dust from cooler and replace thermal paste if you have some. Compressed air applied externally might do the job as well, but sometimes it can make things worse if it frees chunks of crap that get the whole fan stuck.

https://www.youtube.com/watch?v=o-MOZZPAw0Y