Why is one chip design sold as many models?

Factories test every chip and sort it by speed and power, then sell each group as a different model. That is binning.

1. No two chips are the same
Chips made from one design on one wafer still differ a little. Some run faster and some waste more power, like eggs from one farm that differ in size.
2. Test and sort into bins
Every chip is tested for speed, wasted power and faulty parts, then sorted into bins like eggs. Each bin becomes a model, a SKU (stock keeping unit); a chip with a faulty core can be sold with that core off.
3. Set once at the factory
Unlike an egg, each chip also gets one-time switches, set at the factory and never changed. They store its model, its voltage settings and a power limit range; laptop makers pick limits inside it.
4. Each chip's lowest safe voltage
Even chips in one bin differ, so each chip gets its own lowest safe voltage for each speed. Engineers call this adaptive voltage scaling; it saves power.
5. One design, many power targets
The same design can be set to different power targets. A thin laptop chip is often set to 15 to 28 watts (W) to save battery; a desktop chip to 65 W or more.

Words to know

SKU (stock keeping unit): One model of a product, with its own name.
Wafer: A thin, round slice of silicon holding many chips.
Binning: Sorting tested chips into groups by speed and power.
One-time switch: A tiny switch the factory sets once; it cannot change later.
Adaptive voltage scaling: Giving each chip its own lowest safe voltage.
Power target: The steady power limit set for a chip in one device.
V and W: Volts and watts: units of voltage and power.

Testers list every model and setting they must test, because one design can act a little differently in each.

Why can two chips of one design be sold as different models?Think first, then tap to see the answer.

Each chip differs a little, so testing sorts them into bins sold as different models.