Bob Swan, then-interim chief executive officer and chief financial officer of Intel Corp., reacts during the inauguration of the company's research and development facility in Bengaluru, India, on November 15, 2018.

PC makers are pointing at Intel as they tell Wall Street to expect lower revenue. Intel shares fell as much as 1.7% on Wednesday morning after both Dell and HP called out the chipmaker by name in earnings reports Tuesday evening.

Intel remains central to the PC supply chain, although it has faltered at a crucial time, as companies look to upgrade from the Windows 7 operating system, which Microsoft will stop supporting in January. The difficulties have created an opening for smaller rival AMD.

Supply issues have hit Intel for a few months at a time in the past 30 years or so, but the current episode has been going on for a year or more, analyst Patrick Moorhead of Moor Insights & Strategy told CNBC in an interview on Tuesday. Supply is the biggest challenge Intel faces in the short term, he said.

"The first thing Bob said when he got in is, 'This isn't going to happen under my watch,'" Moorhead said, referring to Bob Swan, who took over as permanent Intel CEO in January, replacing Brian Krzanich.

Last week, though, Intel told customers that it was running short on PC processors.

"Despite our best efforts, we have not yet resolved this challenge," Michelle Johnston Holthaus, executive vice president of Intel's sales, marketing and communications group, wrote in a letter.

On Tuesday Dell issued new, lower revenue guidance for its 2020 fiscal year, which will end on Jan. 31, 2020. The $91.5 billion to $92.2 billion forecast came in below the $93.54 billion consensus estimate among analysts polled by Refinitiv. The high end of the range was $2.3 billion lower than what Dell had called for earlier. Dell's stock slid more than 4% in after-hours trading.

"The reduction of the range is principally due to the Intel supply dynamic," Tom Sweet, Dell's finance chief, told analysts on a conference call.

HP did not provide revenue guidance when it reported earnings on Tuesday, but its chief financial officer, Steve Fieler, said on a conference call that Intel's situation could affect HP's revenue, even if the results would be less pronounced on the bottom line as people opt for more profitable products.

HP CEO Enrique Lores said Intel supply constraints would have an impact for at least two quarters.

"Intel is still a very large part of our portfolio and therefore where there are shortages, we need to navigate through those and manage our business that way," he said. HP sells some PCs with AMD chips.

The timing of Intel's supply struggles is not ideal. Technology research firm Gartner estimated that PC shipments increased on an annualized basis in the second and third quarters, citing the move to upgrade to Microsoft's Windows 10. In the third quarter Microsoft's OEM Pro revenue, from Windows licenses for commercial PCs, grew 19%, the fastest growth rate since 2014. Amy Hood, Microsoft's chief financial officer, attributed the spike to "strong Windows 10 demand and momentum in advance of the Windows 7 end of support."

AMD could pick up more business from major PC makers in the coming quarters as Intel's issues persist, Moorhead said. AMD shares are up 111% since the start of 2019.

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