TDP(Thermal Design Power)
A rough measure of how much heat (and roughly power) a CPU produces under load.
For an always-on server, a low-TDP CPU (like Intel's N-series at ~6–15 W) keeps your electricity bill and cooling needs down.
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UPS(Uninterruptible Power Supply)
A battery backup that keeps your server running briefly during a power cut and enables a safe shutdown.
Wake-on-LAN(WoL)
A feature that powers on a computer remotely by sending it a special network packet.