An executive at the memory chip maker Micron Technology said last week at an investor conference that demand for consumer PCs is slowing and that some of its customers have more chips lying around.

A day later, Morgan Stanley downgraded several chip stocks in a note titled "Winter is Coming". The analysts said PC inventory is rising and that the smartphone market is likely to experience similar deterioration.

Global PC shipments grew by 13 percent in the second quarter, according to research firm IDC. That was below Evercore ISI's expectation of 18 percent and a big deceleration from the 55 percent rise in the first quarter.

Some chip analysts have said reports of weakness are primarily seasonal and that sales will pick up through next year. Shortages also vary by part. There are plenty of laptops out there now but nothing for new cars, GPUs or video game consoles.

In some cases, chip delivery times are longer than 20 weeks, the longest wait in at least four years.

The waning demand for PCs will likely last for at least several more quarters.