A desktop computer is a team of parts that each do one job, all plugged into one big circuit board.
- Power supply (PSU) turns the wall's high-voltage AC into steady low-voltage DC that the chips can use.
- Motherboard is the "city streets": it connects every part and carries power and data between them.
- CPU is the brain. It follows the program's instructions one after another, billions of times per second.
- RAM is the desk space: fast, short-term memory for whatever is open right now. It forgets everything when power goes off.
- SSD is the filing cabinet: slower than RAM, but it keeps your files and the operating system even when the PC is off.
- Graphics card (GPU) is a specialist artist that draws every frame you see and sends it to the monitor.
- Cooler and fans carry away the heat all that work makes.
The flow in one sentence: power comes in, the firmware wakes the CPU, the CPU copies the operating system from the SSD into RAM and runs it, the GPU turns the results into pictures, and fans push the heat out.
About accuracy: sizes follow real standards where they exist (ATX motherboard 305 × 244 mm, ATX power supply 150 × 86 × 140 mm, M.2 2280 SSD 22 × 80 mm, RAM stick about 133 mm long), but the case, cooler and graphics card are "typical" sizes — real ones vary a lot. Exact positions of small things like the firmware chip, the M.2 slot and the SATA ports differ between motherboard models. Cables are drawn in front of the board so you can see them; in tidy real builds most run behind the motherboard tray.
Sources: Wikipedia articles on ATX, motherboard, PCI Express, M.2 and UEFI; Intel ATX power supply design guides. Built entirely from code-generated shapes and textures with Three.js.