Member Avatar for SRCross

I did see this thread before, but since it was an old post, decided to start a new one.
I have a Toshiba Satellite A85 Laptop. Battery, charger and port are all fine. Cleaned
fan and heat sinks applied new heat sink compound to CPU. Laptop CPU still runs at 100%
then shuts down. Idle can last all night but running anything will make CPU stay at 100%.
Replace CPU with a new one (refurbished). no change. Possible bad new CPU? or am I over looking something?
Thanks
SRCross

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Given what has already done (cleaned the fan, refreshed the thermal compound and fitted a replacement CPU) the fault narrows to two broad areas: something in the software/driver/interrupt stack driving the CPU to 100%, or a hardware/power/thermal control problem that only shows up under load. The suggestions from and are on point; the following expands those ideas into an ordered, practical diagnostic checklist and what each outcome implies.

Recommended diagnostic checklist (order matters):

  • Repro vs evidence: note whether the shutdown is an immediate power loss or a graceful Windows shutdown. Immediate loss points toward thermal/power; graceful shutdown usually indicates an OS/kernel event (check Event Viewer for Kernel-Power events and thermal notices).
  • Isolate the OS: boot from a clean external USB/live environment and run a CPU load for a short time. If the machine stays up, the problem is likely software/driver. If it dies, hardware is likely.
  • Observe cooling under load: verify the fan actually spins up and watch core temps in BIOS or with a hardware monitor. A fan that does not ramp or temps that jump rapidly implicate fan controller, sensor, or heatsink contact.
  • Re-check heatsink mounting: uneven pressure, excess or too little paste, or a mis-seated heatsink can still cause rapid shutdowns even after a paste job.
  • Firmware/compatibility: confirm the replacement CPU is fully supported by the laptop BIOS and chipset; try a BIOS update or CMOS reset if appropriate.
  • Visual board inspection: look for bulging capacitors, burnt MOSFETs or discolored areas near the VRM; power-stage failures commonly fail under load.
  • Software-level traps: use a detailed process/DPC monitor (Process Explorer or Resource Monitor) to check for driver/interrupt storms if the external OS test passes.

If a clean external OS shows the same immediate shutdown and the fan/sensor behavior is abnormal, the most likely culprits are motherboard power-delivery or fan-control hardware. That generally requires board-level repair or replacement. Safety note: always remove battery and AC before probing hardware, and avoid extended stress runs on a machine that is already unstable.

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Member Avatar for faroukmuhammad

Try using a live CD and see if the PC exhibits the same behavior. If it does'nt then it is a software problem not a hardware one.

Edited by faroukmuhammad because: n/a
Member Avatar for Raimucka

My gues is, tha there is a good probobility of virus infection in windows software.

faroukmuhammad sujested realy good way to test this. Just gooogle up some live cd and after writing it to disc, run on that pc so test it. If it's a saftware problem, then you may consider formating HDD and reinstaling Operating system.
:)

By the way what are you calling "shuts down" pc turns of emediatly after a wile or you see closing aps and looks like a real shuts down?
If it turns of emediatly, then my guess is CPU overheats after a 100% load for a wile. And you may look for the dust in fan and coolin grid or lokking foe better cooler.

But it's just my guess.

Member Avatar for jingda

CAn you check why application is running your CPU up to 100%? You might want to do a scan with malwarebytes .

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