Lenovo has been experiencing steady growth for the last few quarters and according to one estimate it was able to tip the scale in its favor during Q3 2012 to become the world's largest PC manufacturer by volume. Market research firm Gartner says the Chinese manufacturer grabbed 15.7% of the market with 13.77 million units shipped during the quarter, with HP taking 15.5% and yielding its almost six-year reign in the process.

According to IDC estimates, however, Lenovo came very close but didn't quite surpass HP. Their figures show HP retained its leadership position with 15.9% of the global PC market compared to Lenovo's 15.7%.

Gartner: Top 5 vendors, worldwide PC shipments, third quarter 2012 (preliminary)

Company 3Q12 shipped 3Q12 market share 3Q11 shipped 3Q11 market share Growth
Lenovo 13,767,967 15.7% 12,536,756 13.1% 9.8%
HP 13,550,761 15.5% 16,217,987 17.0% -16.4%
Dell 9,216,638 10.5% 10,676,513 11.2% -13.7%
Acer 8,633,267 9.9% 9,616,572 10.1% -10.2%
Asus 6,380,690 7.3% 5,708,807 6.0% 11.8%
Others 35,954,748 41.1% 40,683,666 42.6% -11.6%
Total 87,504,080 100% 95,440,301 100% -8.3%

IDC: Top 5 vendors, worldwide PC shipments, third quarter 2012 (preliminary) 

Company 3Q12 shipped 3Q12 market share 3Q11 shipped 3Q11 market share Growth
HP 13,946,000 15.9% 16,679,000 17.4% -16.4%
Lenovo 13,824,000 15.7% 12,543,000 13.1% 10.2%
Dell 9,499,000 10.8% 11,039,000 11.5% -14.0%
Acer 8,414,000 9.6% 9,307,000 9.7% -9.6%
Asus 6,381,000 7.3% 5,798,000 6.0% 10.0%
Others 35,732,000 40.7% 40,714,000 42.4% -12.2%
Total 87,795,000 100% 96,080,000 100% -8.6%

Regardless of which figure is accurate it's clear HP is the one struggling. The company saw a 16.4% decline in shipments year on year while Lenovo has grown around 9.8% to 10.2% in the same period. Both reports also have Dell in third place, with Gartner reporting that the company has 10.5% of the market and IDC reporting that it has 10.8%, resulting in a 13.7% to 14% decline from Q3 last year.

Yesterday iSuppli reported that PC worldwide shipments in 2012 are expected to decline for the first time in nearly 11 years. In general, analysts blame the continuing slowdown to the rise of portable devices like smartphones and tablets, as well as a "transitional quarter" ahead of the launch of Windows 8.