Chip-making underdog Advanced Micro Devices (AMD) edged past Intel last month in supplying processors for the U.S. retail PC market, according to a study by research firm Current Analysis.

Intel has a firm hold on the overall number-one chip supplier spot for all U.S. consumer PCs, thanks in part to its exclusive deal with direct-selling powerhouse Dell. Still, AMD's October milestone illustrates the progress it has made in eating away at Intel's dominance.

Current Analysis, with headquarters in Washington, D.C., collects its data by surveying major U.S. consumer-electronics retailers. In October, AMD processors were in 49.8 percent of the PCs those retailers sold, compared with a 48.5 percent share for Intel.

AMD brushed past Intel in desktop sales in September. An uptick in its notebook sales as well in October gave it the overall edge over Intel for that month, according to AMD's report.

"AMD did the unthinkable by surpassing Intel in October. Continuing to hold this lead in the holiday season would be a colossal win for the company," Current Analysis Director of Research Matt Sargent said in a written statement accompanying the firm's report.

While AMD gained a slight upper hand on market share, Intel is still the clear revenue winner, thanks to the higher average selling price of Intel-based PCs. Intel's revenue share of retail PC sales in October was 57.6 percent to AMD's 40.1 percent, according to AMD's research.