"This marks the fifth consecutive quarter of declining shipments, which is the longest duration of decline in the PC market's history," Gartner said in a statement.
The company's estimates were released at around the same time as IDC's and largely mirrored its observations on the market.
(IDC is owned by International Data Group, the parent company of IDG News Service.)
Martyn Williams covers mobile telecoms, Silicon Valley and general technology breaking news for The IDG News Service. Follow Martyn on Twitter at @martyn_williams. Martyn's e-mail address is firstname.lastname@example.org