Apple's latest MacBook Pro laptops came with a number of upgrades to processor speeds, RAM and hard drives -- not to mention reduced price tags.

Apple also reduced something else: the serial-ATA (SATA) drive interface, which dropped from 3Gbps on earlier MacBook Pros to 1.5Gbit/sec. on newer ones.

Read our review of the new MacBook Pro's performance here.

The downgrade was initially picked up by Mac aficionados on the MacRumors.com Web site. Computerworld then confirmed the SATA change on a new 15-in. MacBook Pro as well as on the smaller, 13-in. model.

The issue has cropped up on Apple's forums and on notebookreview.com.

It was not clear whether the SATA interface on the latest 17-in MacBook Pro or the ultra-thin MacBook Air were also revamped. Computerworld was unable to get an explanation from Apple about the change.

The move to a slower SATA interface has tech experts baffled, leading them to question whether Apple had encountered technical issues associated with the faster interface.

"I'm puzzled by it, as I know a lot of other people are. The only reason why I could think they would do it is there was some serious technical glitch -- maybe the [processing] chip, maybe the optical drive," said Tom Coughlin, founder of data storage consultancy Coughlin Associates.

Coughlin said some industry rumors indicate there were issues with data transfer rates associated with the MacBook Pro's optical drive, which has a 1.5Gbps interface, "but usually the newer SATA interfaces are downward compatible with older interface products," he added. "So I don't even know why that would be a problem."