The final numbers are in showing that PC makers shipped fewer machines last year than in 2011, and Windows 8 is among several factors being blamed by IDC for the decline, which is expected to continue this year.
Looking back IDC found that in 2012 total worldwide shipments of PCs was down 3.7 percent, including desktop and portable PCs.
The trend was worse in mature markets - the US, Canada, Western Europe and Japan - with a dip of 4 percent. Emerging markets - Asia/Pacific, Latin America the Middle East and Africa - were down 1.4 percent.
Limited interest in Windows 8 led last year to a dismal fourth quarter, IDC says in its latest Worldwide Quarterly PC Tracker. Volume dropped 8.3 percent in Q4 2012 compared to Q4 2011, wiping out a potential bump during the normally robust holiday sales quarter, IDC says. That's the largest drop ever recorded for a holiday season.
IDC described the reception of Windows 8, which launched in October, as "underwhelming." Also contributing to the slow fourth quarter were tight IT budgets and a continuing poor world economy.
Hurting the potential lift that Windows 8 might have provided was the lack of components for touchscreen devices - the type of machine Windows 8 was designed to work best on. That makes the touchscreen devices that are available seem expensive compared to non-touch devices, IDC says.
Still, Windows 8 could help PC sales rebound somewhat late this year, says Rajani Singh, a research analyst at IDC.
"IDC expects the second half of 2013 to regain some marginal momentum partly as a rubber band effect from 2012, and largely thanks to the outcome of industry restructuring, better channel involvement, and potentially greater acceptance of Windows 8," he says. But it still won't be enough to register growth; IDC projects worldwide PC sales in 2013 to drop another 1.3 percent.
The end of support for Windows XP should force more PC upgrades later this year as well, which could help bolster shipments later in 2013, Singh says.
The study doesn't include tablets because they aren't the functional equivalents of PCs, but their popularity among consumers helps siphon off dollars that otherwise might be spent on PCs, says Loren Loverde, vice president for Worldwide PC Trackers at IDC.
"Growth in emerging regions has slowed considerably, and we continue to see constrained PC demand as buyers favor other devices for their mobility and convenience features," Loverde says.
Long-term shipments of PCs shows better but still modest growth, the report says, projecting a 9 percent increase between 2012 and the end of 2017.