Apple may be preparing another stealthy hardware upgrade, this time for its Power Mac G4 Server range.

As Macworld reported last week, the company has withdrawn its older Power Mac G4 Servers from sale. This was seen by analysts as an attempt to stimulate Xserve sales.

Now, a small ad on Apple's US Apple Store reads: “Need a Macintosh G4 Server? Coming soon.”

The image for the ad shows a new G4 Power Mac chassis, with the distinctive row of four apertures on the lower half of the front casing. It now appears the older models were withdrawn in order to introduce models based on the new chassis.