According to iSuppli Corp.’s market intelligence, nine months after losing its customary No. 2 rank in the global PC market, U.S. OEM Dell Inc. retook the runner-up position in the second quarter of 2010 as Taiwanese rival Acer Inc. suffered a sales setback during the period.

Dell in the second quarter shipped 10.5 million units worldwide, down a negligible 1.2 percent from 10.7 million units in the first quarter. This gave Dell a 12.8 percent share of global shipments, down from 13.1 percent in the first quarter.

However, Acer experienced a 6.2 percent shipment decline in the second quarter, with its shipments falling to 10.2 million units, down from 10.9 million in the first quarter. As a result, Acer’s share declined to 12.4 percent, down from 13.3 percent in the first quarter, consumer electronics research from iSuppli indicates.

Acer’s decline was notable given the global PC market’s 1.1 sequential rise in the second quarter, with shipments amounting to 82.5 million units, up from 81.6 million in the first quarter.

“With its product line heavily focused on mobile PCs, Acer’s sequential decline in notebook shipments impacted its position at the total PC level more than its competitors, which were able to draw on the upswing in desktop shipments to bolster their total shipments,” said Matthew Wilkins, Principal Analyst (Compute Platforms) for iSuppli.

iSuppli’s computer comparisons show, U.S.-based Dell perennially had occupied the No. 2 position in the global PC market behind fellow American PC maker Hewlett-Packard Co.

Dell’s share of the global PC market had been steadily declining since the second quarter of 2008, when the company accounted for 16 percent of worldwide shipments and held a 6.5 percentage point lead over Acer.

However, by the third quarter of 2009, Dell’s share had dwindled to 12.9 percent, allowing Acer to slip past and take the world’s No. 2 position.

“The second-quarter results show the market-share battle between Dell and Acer is not over and that it will continue to rage,” Wilkins said.

While shipments declined sequentially for Dell and Acer in the second quarter, both companies achieved robust growth compared to the same period in 2009. Dell’s shipments rose 16.7 percent from a year earlier, while Acer’s soared by 24.2 percent, as the overall market expanded by 22.8 percent.

Acer’s strong performance relative to the second quarter of 2009 was driven by the expanding sales of notebooks, which accounted for about 80 percent of the company’s total PC shipments in the second quarter, according to iSuppli notebook research. In contrast, Dell appears to be benefitting on a rebound of corporate demand for desktop PCs and entry-level servers.

The benefits extended as well to other OEMs whose PC shipments include a somewhat equal mix of desktops and notebooks. Desktop PC shipments among the Top 5 desktop PC OEMs grew in the region of 12 to 15 percent.

iSuppli’s latest worldwide PC forecast calls for unit shipment growth of 15 percent in 2010. The second quarter marked HP’s 16th consecutive quarter as the No. 1 worldwide PC brand, with a market share of 18.1 percent.

For their part, the Top 5 Asian OEMs all delivered strongly, with great performances equaling or surpassing 24 percent year-over growth rates. Lenovo led the Asian OEMs, growing its PC shipments by 47.5 percent from the second quarter of 2009, resulting in a market share increase of 1.7 percent year-over-year.