An 850W power supply is usually unnecessary for AutoCAD 2D drafting unless the computer also carries a power-hungry graphics card or a planned future upgrade. Drafting performance depends more on the processor, memory, storage and application stability than on unused PSU capacity.
Size power for the complete parts list
Choose the processor and graphics card first, then use their official power guidance and a reputable calculator. Include drives, fans and USB devices, and leave sensible headroom for sustained loads. Connector type, build quality, efficiency, protections and warranty matter more than chasing the largest wattage number.
The factpacks verify the Corsair RM850e 850W modular power supply at R1,900. It is a relevant option for a higher-draw build with suitable connectors, but 2D drafting alone does not justify it. The DeepCool PF750 750W power supply appears at R550 as a lower-cost reference. Do not choose either unit without confirming the complete component load, case fit and required CPU and GPU cables.
A system using integrated graphics or a modest GPU may need far less capacity. Spend the difference on dependable storage, enough memory, backups or a suitable monitor if the measured build allows it. Never reuse an unknown modular cable from another power supply, even when the plug appears to fit.
Powering a drafting workstation? > Compare verified Evetech PSUs after checking the full parts list, connectors and upgrade plan.