CPU (CPU)

CPU stands for central processing unit, the main programmable processor chip in any computer that fetches, decodes, and executes program instructions. CPUs from desktops, laptops, servers, and workstations form a small but extremely high-value fraction of the Indian e-waste stream. Although a typical desktop or laptop motherboard carries only one CPU, that single chip contains a disproportionate share of the motherboard's total precious-metal value.

Why CPUs are precious-metal-dense: A modern desktop CPU package weighs 25-55 grams and contains hundreds of fine gold wire bonds between the silicon die and the package substrate, gold-plated pins (in older LGA/PGA sockets, typically 1,150-2,066 pins per CPU) or solder balls (in BGA packages), palladium-bearing solder, and silver-loaded thermal interface materials between the die and the heatspreader. Gold concentrations in clean CPU scrap reach 800-1,800 grams per tonne — comparable to the richest IC scrap and 150-300 times the gold content of primary ore. Indian PCB processors typically pay Rs 5,000-12,000 per kg for clean CPU lots, against Rs 800-1,500 per kg for mixed motherboard PCB.

Identification and segregation: CPUs are physically distinctive — they are the largest single chip on any motherboard, mounted in a square socket with a metal heatspreader on top. Manual dismantlers can remove CPUs in 30-60 seconds per board using a screwdriver and pliers. The Indian formal recycling sector sorts CPUs into three quality bands by visual inspection: ceramic-substrate CPUs (the oldest Pentium-era chips, richest in gold pins), gold-cap CPUs (mid-vintage), and modern integrated-heatspreader CPUs (lowest gold content per gram but highest absolute volume).

Trade-offs: The economic question for Indian recyclers is whether to refine CPUs internally or sell them to specialist refiners. Internal hydrometallurgical processing yields 92-95% of contained gold but requires aqua-regia handling, neutralisation, and effluent treatment with significant CapEx (Rs 50 lakh-1 crore). Selling clean CPU lots to refiners in Singapore, Japan, or Belgium captures 80-85% of theoretical metal value (after refining margin) with zero internal CapEx — the preferred route for plants processing under 100 kg of CPU per month.