PC shipments in the U.S. declined by 5.7 percent year over year, and shipments in Latin America declined by 1.7 percent, Gartner said. Factoring in Western Europe, overall shipments in EMEA (Europe, Middle East and Africa) grew by 1.9 percent. Shipments in Asia-Pacific grew by 2 percent, and shipments in Japan also grew by 2 percent.

The slowdown has hurt chip makers as well as PC makers. Advanced Micro Devices reduced its revenue expectations earlier this week on poor consumer spending and weak sales in China and Europe. The company said its OEM (Original Equipment Manufacturing) business underperformed, indicating that PC makers bought fewer chips than expected.

Intel is making a push to revitalize PC shipments with ultrabooks, a category of thin and light laptops that became available starting in late 2011. Intel has poured millions into developing and promoting ultrabooks, but so far they have failed to reignite laptop shipments, Kitagawa said. Ultrabooks are at an early stage and a new batch based on Intel's third-generation Core processors are slowly becoming available.

But the second-quarter slowdown does not bode well for ultrabooks, nor Microsoft's upcoming Windows 8 OS, due later this year, Gartner said.

HP shipped 13 million PCs in the quarter, a drop of 12.1 percent, giving it a 14.9 percent market share. Second-place Lenovo grew its shipments by 14.9 percent to 12.8 million units, giving the Chinese PC maker a 14.7 percent market share.