Worldwide PC microprocessor sales slowed during the third quarter due to weak consumer demand, according to a report released on Thursday.

Market demand for processors was weak in July and in August, said Shane Rau, director of PC-related semiconductor research at International Data Corporation (IDC).

PC vendors reacted to slowing demand by cutting orders for processors and other components, IDC says.

The whole supply chain is skittish, Rau added.

The market share of Intel decreased to 80.4 percent in the third quarter, down 0.7 percent compared with the same quarter last year, IDC said.

On the other hand, Advanced Micro Devices (AMD)’ share increased to 19.2 percent from 18.7 percent.

Also, Intel lost share in the lucrative mobile processors market in the third quarter. The company’s market share fell to 85.9 percent in the quarter, down 1 percent compared with same quarter a year earlier. The mobile processors market includes chips for laptops, netbooks and other devices.

However, AMD increased its share to 13.7 percent from 12.6 percent in the mobile processors market globally.

IDC estimates the demand will improve in the fourth quarter as the PC vendors produce devices with Intel's Sandy Bridge processors inside and AMD's Fusion processing architecture is launched.

We believe that the fourth quarter of 2010 will be a decent quarter, added Rau.

But the second half growth will be lower than the first half year-on-year, says IDC.

For 2011, we believe that, even though the consumer segment will remain stalled in developed regions, IT executives will see PC upgrades as a priority over the next 12 months which should result in double digit growth in PC systems and PC processors units next year, IDC predicts.