Intel has announced an even faster 2.8GHz revision of its Core 2 Extreme dual-core notebook CPU.

The new Core 2 Extreme X7900 ups Intel's mobile ante by 133MHz from its predecessor, 2.66GHz Extreme X7800. Just like that chip, the new Extreme X7900 has a 44 Watt power rating. Non-Extreme members of the Core 2 mobile range top out at 35 Watts.

Like other recent Core 2 mobile processors, the new chip supports an 800MHz CPU bus and packs 4MB of Intel's Smart Cache memory. But the X7900's increased power consumption and heat dissipation makes it unsuitable for use in most small form factor thin-and-light notebooks. Unlike cooking Core 2s, the Extreme X7900 boasts an unlocked CPU multiplier. That's a feature that makes overclocking much simpler and is designed to appeal to enthusiasts.

Extreme X7900

The Extreme X7900 is likely to be the swansong for mobile processors based on Intel's 65nm production process. New 45nm mobile chips are due to go into production later this year.

Intriguingly, it was Apple's latest iMac desktop that was first to use the X7900. We noted in our launch coverage earlier this month that the range-topping iMac was being offered with an optional 2.8GHz Core 2 Extreme CPU. A chip that did not appear in Intel's existing price lists at that time. Now we know why. It hadn't officially been launched.

It's the first time a new Intel processor has debuted in an Apple product and suggests that the two companies are cosier than ever.

The Core 2 Extreme X7900 goes on sale at $851 (£424) in 1,000-unit quantities. No word as yet on UK retail pricing. However, the vast majority of mobile CPUs are sold as part of a complete notebook PC.