Nick Race03 November 2008, 3:00 PM
This smoking new CPU from Intel does away with Frontside Bus altogether and brings a technology back from the dead.
Page 3 - Death of Frontside Bus means better connection of multiple processors
The biggest news in the Nehalem family is that the FSB is no more. As the FSB has become a bottleneck in modern Intel systems (hence the constant increases in FSB speeds in recent years), Intel replaced the FSB with a new communications path named QuickPath Interconnect.
QPI can handle up to 6.4GT/sec using an Extreme Edition processor or 4.8GT/sec in lower performance chips between the IOH (northbridge) and other processors in a multi-CPU setup. Compared to 1333MT/s FSB bandwidth of Penryn, that’s a significant speed increase.
(GT/sec stands for Gigatransfers per second -- you can read more about it here.)
Communication with the system RAM is done directly from the CPU, bypassing the northbridge altogether, leaving more bandwidth available for IO.
QPI is a more efficient way of moving data around a platform as it’s a point to point system. This will, understandably, increase the complexity of motherboards especially in a multi CPU system, but because there are no third party stops along the way for a data path, communication directly between a CPU devices like the IOH (northbridge) and other CPU’s memory sees substantial increases in performance.
Unlike the Skull Trail platform’s use of an entry level server/workstation board to support a dual processor system, X58 already includes two QPI endpoints, allowing two physical CPUs to be connected.
The matching CPUs with two QPI connections allowing a dual processor setup is codenamed Gainestown, but no specific announcements about Gainestown compatibility with X58 has been made.