Hewlett-Packard and Lenovo are slugging it out for the top spot in the flagging market. Gartner said that Lenovo slipped past HP to claim the number-one spot in the PC arena with 15.7 percent of the global PC market compared to 15.5 percent for HP. For its part, IDC reported that HP hung on to the top position with 15.9 percent of the market compared to Lenovo's 15.7 percent.

Last week at its annual financial analyst day Wednesday, HP CEO Meg Whitman said the company has a tough game of catch-up to play in hardware over the next few years. HP forecast earnings per share of US$3.40 to $3.60 for this fiscal year, below the prior estimate of $4.18 from analysts polled by Thomson Reuters. Whitman said the company needs to come up with a hit next-generation smartphone or other mobile device in order to maintain a leadership position over the next few years.

Meanwhile, even the mighty , both IDC and Gartner said. IDC said Apple sold 2.06 million Macs in the quarter, a drop of 7 percent year over year. Gartner said the decline was 6.1 percent.

The PC slump is affecting chip makers as well.

In a preliminary financial report, for the third quarter, blaming a tough economy for the decline. Intel's main rival now forecasts revenue for the quarter to drop by about 10 percent from the second quarter, compared to prior estimates that the decline would be no worse than 4 percent.