A user says their Windows 10 desktop was fast yesterday but is now sluggish. Boot completes, yet programs take twice as long to open. Task Manager shows the CPU frequency repeatedly dropping to 800 MHz. Entering UEFI reveals the CPU temperature quickly rises to 95 °C within a minute of power-on, even while idle. Which hardware issue is the MOST likely root cause of the reduced performance?
The power supply's 12 V rail is delivering 12.4 V, causing the CPU to under-volt itself.
Full-disk encryption is still running in the background and consuming resources.
The CPU fan cable is disconnected from the motherboard header, so the fan never spins.
A GPU-based 3D screensaver is constantly rendering while the system is idle.
Modern CPUs automatically lower clock speed (thermal throttling) when internal temperature exceeds safe limits, which immediately slows the system. A CPU fan that is unplugged or has failed prevents heat from being removed, so the temperature skyrockets soon after startup and remains high, forcing the CPU to stay at a reduced frequency. A full-disk encryption process, an over-voltage 12 V rail, or a demanding GPU task could affect performance, but none would make the CPU temperature spike almost instantly when the system is otherwise idle.
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Why does thermal throttling occur in CPUs?
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