Intel's Pentium 4 3GHz With 800MHz System Bus
And The i875P "Canterwood" Chipset
More bandwidth and leading edge desktop technology for the P4

By, Dave Altavilla
and Chris Angelini
April 14, 2003
 

Time certainly does fly when you are clipping along at 3GHz, doesn't it?  It has been a whole 5 months since Intel released their last processor speed bump.  Intel actually let this one ride a little bit it seems.  In early February, AMD let loose with their new "Barton" core based Athlon XP 3000+ (2.166GHz), in an effort to keep pace with Intel's brute force approach to processing.  Don't misunderstand us, there certainly is nothing wrong with "brute force", when it comes to computing.  However, efficiency is also the name of the game and while it is impressive to see a 3GHz CPU like the Pentium 4, in mass production, it's equally as impressive to see a processor like the AMD Barton core, keep step with the P4, while clocked almost 1GHz lower.  The Pentium 4's super deep "hyper pipelined" architecture, that allows it to hit such impressive clock speeds, is also a source of some inefficiency within the chip.  It seems you can't really have your cake and eat it too, because along with this architecture comes the inherent latency associated with a deeper pipeline.  Regardless, like all things in life, there is a balance; a balance between raw clock speed and processing efficiency.  Intel certainly seems to have found that balance and like AMD, they are on a never-ending quest to improve upon the existing architecture.

Another way to enhance P4 performance, is by providing the CPU with more bandwidth via associated bus interfaces.  Simply cranking up CPU clock cycles, will certainly bring you incremental performance.  However, giving the processor enough bandwidth to get out to other system resources and peripherals, is also critical for overall throughput.  Otherwise you'll have the equivalent of a jet fueled Funny Car, sitting in neutral, red-lining the engine and going nowhere fast.  As such, we've witnessed both Intel and AMD taking System Bus (or Front Side Bus) speeds up a notch or two, along the way of their respective roadmaps.  At 2.26 and 2.4GHz, Intel took the Pentium 4 to a 533MHz System Bus, with a Quad Pumped 133MHz reference clock.  This time around, at 3GHz, Intel gives us an 800MHz System Bus, with a Quad Pumped 200MHz reference clock.  However, we are reminded once again, of a lesson taught to us by our Asian friends, that of "yin and yang", or balance.  To compliment this extra bus bandwidth Intel also brought forth Dual Channel DDR400 memory support. 

If this is beginning to sound like a complete system controller overhaul, you would be correct.  Along with this new 800MHz System Bus capable P4, comes Intel's i875P chipset, more commonly referred to as "Canterwood".  And while they were at it, Intel brought many of the peripheral interfaces of their new chipset, up to snuff as well.  The following is a HotHardware.Com overview and performance analysis, of Intel's new Processor and Desktop Platform, based on their new Pentium 4 3GHz with an 800MHz System Bus and the D875PBZ - i875P driven motherboard.

Specifications of the Pentium 4 3GHz Processor
Hyperthreading and a neat clean 800MHz System Bus

  • Clock Speed 3GHz
  • 800MHz "Quad Pumped" Front Side Bus
  • Hyperthreading Technology for increased performance in Multi-tasking and Multi-threaded applications
  • .13 micron manufacturing process
  • 512K on chip, Full Speed L2 Cache
  • Rapid Execution Engine - ALU clocked at 2X frequency of core
  • 128bit Floating Point/Multimedia unit
  • "Hyper Pipelined" Technology for extremely high clock speeds
  • Intel "NetBurst" micro-architecture
  • Supported by the Intel i875P and i865G chipsets, with Hyperthreading support
  • Internet Streaming SIMD Extensions 2
  • Intel MMX media enhancement technology
  • Memory cacheability up to 4 GB of addressable memory space and system memory scalability up to 64 GB of physical memory
  • Support for uni-processor designs
  • 1.525V operating voltage range

Obviously this quick specification list is a repeat for the most part, with one exception.  Intel's new 3GHz Pentium (note the even 3GHz number, rather than 3.06GHz), is now characterized to run on an 800MHz System Bus with a Quad Pumped 200MHz reference clock and DDR400 Memory Bus.  Who would have thought we would see an FSB of 200MHz as a "stock" clock speed on any motherboard?  Ahhh, but technology does roll on, doesn't it?  This one enhancement alone should boost performance nicely, especially in system bandwidth demanding applications.

Specifications of The i875P Canterwood Chipset
800MHz System Bus, Dual Channel DDR400, "Native" SATA - You've got to love it

With the launch of Intel's new "Canterwood" chipset, we're given a new Northbridge and a new Southbridge to work with, along with all of the latest creature comforts.  What, no passenger side airbag?

PAT - Performance Acceleration Technology:

Intel has optimized the performance of the Canterwood chipset's memory controller and improved on latency characteristics in two key areas, DRAM Chip Select and Memory Controller Access.

There is a resultant 2 clock improvement for Canterwood, which should help somewhat.  Intel is calling this "PAT", Performance Acceleration Technology.  Frankly this feels like a bit of Marketing spin.  We should also note that for some reason, although we could set 2, 2, 2, 5 timings, for the PC3500 DDR Memory we used in testing at 400MHz in other boards, we could not get beyond  2, 3, 3, 5 timings with this new Intel D875PBZ board.  It seems as though Intel's new chipset is a little less forgiving with respect to aggressive memory timings.  However, we're sure Memory OEMs will be targeting full performance with this chipset, so it probably won't be long before better memory is available, that can support aggressive timings like we've seen with the i845PE.

CSA - Communications Streaming Architecture:

Both Canterwood and the upcoming Springdale chipset share a new Networking technology from Intel called "CSA".  CSA is essentially a direct link to the Northbridge System Controller, versus utilizing the PCI bus.  This allows Intel's Pro/1000CT MAC/Phy controller direct access to system memory, with higher overall bandwidth at 266MB/sec, twice that of PCI, as well as reduced CPU utilization.  The benefits are obvious.

  • Direct Access to System Memory

  • Prioritized Access to GbE traffic

  • 1.5V Interface

  • Low Latency Design

  • 266 MB/s dedicated to Networking I/O

  • Reduced CPU Utilization

  • Better management of simultaneous data streams

  • Lower GbE component power

  • Bursts of network traffic handled with ease

We had a relatively short window of time to test this new Intel platform and as a result, we're not able to provide you back-up factual analysis to support these claims.  However, we can report that during testing and routine use on a 100Mb Ethernet Network, the Pro/1000CT Controller performed admirably with excellent throughput and reliability.

A Closer Look, System Setup and Sandra