Gartner and IDC have both released figures for worldwide shipments  of personal computers in the third quarter of 2013, revealing that demand for PCs has reduced for the sixth quarter in succession.

Because they use different definitions of Personal Computer, Gartner and IDC differ in the details. Gartner said the market shrank by another 8.6 percent to 80.3 million units in total while IDC reported a decline of 7.8 percent and a total of 81.6 million units.

Both companies agree that Lenovo has around 17% market share and saw a modest growth compared to the same quarter last year, 2.8% according to Gartner and 2.2% according to IDC. HP and Dell also saw tiny amounts of growth and it was Acer and Asus that bore the brunt of the decline. Gartner reports a fall around 34% for each of them while according to IDC it was around 22%.

Both IDC and Gartner pointed to signs of recovery for the US market with Gartner reporting 3.5% growth overall there with Lenovo experiencing a upturn of 24.6%.

Commenting on the global scenario, in which sales dropped to their lowest volume since 2008, Mikako Kitagawa, principal analyst at Gartner said:  

"Consumers' shift from PCs to tablets for daily content consumption continued to decrease the installed base of PCs both in mature as well as in emerging markets. A greater availability of inexpensive Android tablets attracted first-time consumers in emerging markets, and as supplementary devices in mature markets."

This explanation is neatly illustrated in a chart from Howard Dediu of consulting firm Asymco which shows how PC shipments have slumped since second quarter 2010 and linking this to the launch of the iPad:

However, while it is attractive to ascribe a single cause for the decline it seems more likely that PC shipments have shrunk for a variety of reasons. True, the first is the rise of the mobile and tablet device. If you want to consume information and apps then you can do it just as well with a low cost device as a PC. This means that many users who would have bought a PC simply to gain access to the web are now happy surfing using a tablet or even their mobile phone. 

There is also the fact that the PC hasn't increased significantly in power for a few years and this has reduced the need to upgrade to ensure that the software will run. In short, today's desktop software is just as happy on yesterday's PC.

Finally the failure of Microsoft to convince end users that Windows 8 is the operating system to upgrade to has made a new PC seem like something that is worth putting off. Any user remembering the Vista flop will be waiting for whatever comes after Windows 8 before buying a new machine.