Supply chain sources suggest they've had enough.
Taiwanese news site Digitimes says these four 'old-school' PC makers have recognised they can't compete with OEMs that combine a hardware build with a tightly integrated software offer – namely Apple, Amazon and Barnes & Noble.
These end-to-end devices don't just offer a more compelling proposition to users, they're also cheaper. Amazon is offering its Kindle Fire at $199 and Barnes & Noble's Nook Simple Touch is $99. They may even end up free one day.
The Guardian surmises that the four exiting OEMs may be waiting for a WinPho tablet option as this would prove more attractive to the vast Microsoft-addicted enterprise market.
Although it does point out that margins are tight in Microsoft world, with Hewlett-Packard making an average profit of just $40 on each $800 PC it sells.
And there's some serious catching up to do even in this space, with Good Technology revealing last month that 19 out of 20 enterprise tablets are iPads.