A technician builds a workstation.

A shutdown during POST combined with a burning smell strongly indicates an overheating condition occurring almost immediately after power-on. In a newly built workstation, the most common cause of rapid CPU overheating is improper heatsink installation, especially failing to apply thermal paste (thermal compound) between the CPU and the heatsink. Thermal paste fills microscopic imperfections between the two metal surfaces so heat can transfer efficiently into the heatsink. Without it, the CPU can spike to unsafe temperatures within seconds. Modern systems detect this and trigger protective thermal shutdown during POST to prevent permanent CPU or motherboard damage. The burning smell can occur when components near the CPU socket heat excessively or when protective coatings/dust residues warm quickly due to poor heat dissipation.

The wrong type of RAM (B) would more likely cause no-boot/beep codes rather than a burning smell. Not properly grounding (A) relates to ESD damage risk, but that typically causes intermittent or dead hardware symptoms, not immediate thermal shutdown. A disconnected case exhaust fan (C) can contribute to higher case temperatures, but it’s less likely to cause an immediate POST shutdown compared to missing thermal paste on the CPU cooler.