Research firm Gartner said worldwide shipments of personal computers fell 7.7% to 73.7 million units in the third quarter as a stronger dollar made them costlier.
Meanwhile, International Data Corporation (IDC) said shipments fell 10.8% to 71 million units.
Up to yesterday's close, the dollar had risen about 5.6% this year against a basket of major currencies.
Gartner also said the Windows 10 launch in the quarter had minimal impact on shipments as users chose to upgrade to Windows 10 on existing PCs.
Gartner said analysts "see some signs for future stabilisation and growth" in the PC market. The firm said in July that it did not expect the global PC market to recover until 2016.
"The PC market continues to contract as expected, but we remain optimistic about future shipments," said Jay Chou, research manager at IDC Worldwide PC Tracker.
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