Towards the end of the year, Intel will be rolling out a quad-core version of the Core 2 and Xeon processor lines, codename Kentsfield and Clovertown, respectively. These processors utilize the same LGA-771 sockets as their dual-core brethren, a fact that raises the question as to whether or not these new processors can serve as drop-in replacements for the Mac Pro's dual-core Xeons.
Current indicates are: yes, indeed they can.
The folks over at AnandTech took a couple of 2.4GHz Cloverton engineering samples and
replaced the Woodcrests in a Mac Pro with them. They worked like a charm, with Mac OS X detecting and fully utilizing all eight cores. The test setup ran with a 1066MHz front-side bus, but AnandTech expects that the final chip will utilize a 1333MHz FSB.
Current indications are that the quad-core units will run at a lower clockspeed than their dual-core siblings, but in situations where heavily threaded applications (or many, simultaneous lesser threaded applications) are run, more cores means a more powerful system.
The future looks bright for those hoping to extend their investment in a Mac Pro with upgrades down the line.