Worldwide shipments of personal computers fell in the third quarter of the year, the sixth straight quarter of decline as cheaper tablet computers and smartphones cut into demand, according to market research firms IDC and Gartner Inc. IDC said the market fell nearly 8 percent, to 81.6 million units, while Gartner put the decline at almost 9 percent, to 80.3 million. The two firms define PCs slightly differently. IDC expects that the PC market will hit bottom sometime next year, with a recovery starting in 2015 as companies and consumers finally replace aging PCs. Gartner says this year will be the worst, with flat shipments next year and single-digit percentage growth in 2015. There's sort of a rubber band effect where PCs that need to be replaced will be, said IDC senior analyst Jay Chou.