Intel plans to introduce a new quad core codenamed Yorkfield and this will be a new Core 2 Extreme. At this point Intel doesn't want to tell a frequency of a chip but this will depend on how fast is Barcelona or Agena FX as a matter of speaking.
The new CPU supports FSB 1333, has up to 12 MB of cache memory quad core and it firsts in LGA 775. This CPU comes in Q1 2008 but some sources close to Intel indicated that if possibly Intel can launch a limited number of these CPUs in Q4.
Published in Processors
Yorkfield Quad core 12 MB Extreme comes
Intel roadmap: After 3 GHz FSB 1333