Intel has expanded its share of the server microprocessor market, taking advantage of a slow product transition at perennial rival Advanced Micro Devices, according to figures released late Wednesday by IDC.

Intel supplied 93.5 percent of the server processor units shipped in the second quarter, up from 89.9 percent in the same quarter last year. AMD's share slipped to 6.5 percent from 10.1 percent over the same period, IDC said.

Most of AMD's share loss occurred between the first and second quarters, when server makers were slow to offer AMD's new 6000 series Opterons in their systems.

"AMD is in the middle of a product transition. It stated in late Q1 and they hoped it would be completed in Q2, but it turns out it took their OEMs a bit longer to ramp up the products they were building," said Mercury Research analyst Dean McCarron.

AMD executives said as much during an earnings call for the second quarter, in which the company swung to a loss after two straight quarters of profit. Intel had a much stronger quarter, thanks largely to growth in its server chip business.

"Intel got significant sales traction for its new 32 nanometer Xeon DP products, formerly code-named Westmere-EP, and for its 45 nanometer Xeon MP products, formerly code-named Nehalem-EX," IDC analyst Shane Rau said via e-mail.

"In contrast, while AMD launched its 8-core and 12-core Opteron products, formerly code-named Magny Cours, OEMs didn't buy them and ship them in significant volume [in the second quarter]. I expect that to change in [the third quarter]," he said.

McCarron also said things could look up now for AMD. "Presumably in the third and fourth quarters they won't be weighed down by those transition issues," he said.

In the wider x86 market, including server, desktop and mobile processors, things looked better for AMD. Its overall market share increased a fraction between the first and second quarters, from 18.8 percent to 19.0 percent of processor units shipped.

AMD's share of laptop processor shipments increased to 13.7 percent in the second quarter, from 12.1 percent in the first quarter, while Intel's share fell from 87.8 percent to 86.1 percent. In desktop processors, Intel added a half percentage point of share from the first quarter, to reach 72.2 percent, IDC said.

Via Technologies accounted for 0.3 percent of overall processor shipments in the second quarter, up from 0.2 percent in the first quarter but down from 0.5 percent in the first quarter last year, IDC said.

Overall x86 processor shipments for all vendors were up 30.8 percent year-over-year in the second quarter, as IT buyers resumed spending on equipment. The mobile sector saw the most growth, followed by servers.

(IDC is owned by International Data Group, the parent company of IDG News Service.)