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s for Intel-based servers and workstations. Amongstthese was one single-processor chipset, the E7205, formerly codenamed Granite Bay.
For some time the most viable way of balancing the bandwidth between the Pentium 4 CPU and its
memory subsystem had been to couple the i850E chipset with dual-channel RDRAM. However, given
the price and availability issues surrounding high-density RDRAM modules, this was a far from ideal
solution. Despite - as its server/workstation class chipset nomenclature implies - not originally being
intended for desktop use, the E7205 chipset was to provide an answer to this dilemma. With a
specification which includes support for:
• Dual Channel DDR266 memory bus (4.2GBps memory bandwidth)
• 400/533MHz FSB support (3.2GBps - 4.2GBps FSB bandwidth)
• AGP 8x
• USB 2.0, and
• integrated LAN.
it didn't take long for the motherboard manufacturers to produce boards based on the new chipset.
The E7205's memory controller is fully synchronous, meaning that the memory in E7205-based
motherboards is clocked at the rate equal to the FSB frequency. Consequently, only DDR200
SDRAM may be used with CPUs supporting a 400MHz FSB and only DDR266 SDRAM with
processors supporting a 533MHz FSB. The E7205 does not support DDR333 SDRAM.
With the Pentium 4 family destined to make the transition to a 800MHz Quad Pumped Bus - at which
time the CPU's bus bandwidth will increase to 6.4GBps - it appears reasonable to assume that the
likely way for memory subsystems to have comparable bandwidth will be the continued use of dual-
channel DDR SDRAM. To that extent, the E7205 can be viewed as a prototype of the Canterwood
and Springdale chipsets slated to appear in 2003.
Intel 875P chipset
Originally, Intel had planned to introduce a 800MHz FSB in the context of the Prescott, the upcoming
90nm Pentium 4 core. However, in the event this was brought forward to the spring of 2003. The
rationale was to extend the Pentium 4's performance curve within the confines of their current 0.13-
micron process, without having to increase clock speeds to unsustainable levels. The transition from
533MHz to 800MHz FSB was aided and abetted by an associated new chipset platform, the 875P
chipset, formerly codenamed Canterwood.
A 64-bit 800MHz FSB provides 6.4GBps of bandwidth between the Memory Controller Hub (or
Northbridge) and the CPU. In a move that appears to further reduce the strategic importance of
DRDRAM in Intel's product planning, and that had been signalled by the earlier E7205 chipset, the
memory subsystem the 875P uses to balance bandwidth between the Memory Controller Hub (MCH)
and memory banks is dual channel DDR SDRAM, all of the DDR400, DDR333 and DD266 variants.
Currently, there are two different strategies being employed in dual-channel memory controllers, one
in which where each memory bank has its own memory channel and an arbiter distributes the load
between them and the other to actually create a wider memory channel, thereby "doubling up" on
standard DDR's 64-bit data paths. The i875P employs the latter technique, with each pair of installed
DIMMs acting as a 128-bit memory module, able to transfer twice as much data as a single-channel
solution, without the need for an arbiter.
As a consequence, dual channel operation is dependent on a number of conditions being met, Intel
specifying that motherboards should default to single-channel mode in the event of any of these
being violated:
Bài giảng KTSC Máy tính H.V.Hà
72
• DIMMs must be installed in pairs
• Both DIMMs must use the same density memory chips
• Both DIMMs must use the same DRAM bus width
• Both DIMMs must be either single-sided or dual-sided.
The 875P chipset also introduces two significant platform innovations:
• Intel Performance Acceleration Technology (PAT), and
• Communications Streaming Architecture (CSA).
PAT optimises memory access between the processor and system memory for platforms configured
with both the new 800Mhz FSB and Dual-Channel DDR400 memory. CSA is a new communications
architecture that creates a dedicated link from the Memory Controller Hub (MCH) to the network
interface, thereby offloading network traffic from the PCI bus. Used in conjunction with the new Intel
PRO/1000 CT Desktop Connection gigabit Ethernet controller, it is claimed that CSA doubles the
networking bandwidth possible with traditional PCI bus-based solutions.
Additionally, the 875P chipset includes a high-performance AGP 8x graphics interface, integrated Hi-
Speed USB 2.0, optional ECC is supported for users that demand memory data reliability and
integrity and dual independent DMA audio engines, enabling a user to make a PC phone call whilst at
the same time playing digital music streams. The chipset is also Intel's first to offer native Serial ATA
(SATA), a special phiên bản designated by the "-R" suffix adding RAID - albeit only RAID 0 (data
striping) - support.
Intel 865 chipset
If the i875 chipset can be viewed as the logical successor to i850E, then its mainstream variant, the
i865 chipset - formerly codenamed Springdale - can be viewed as the logical successor to the i845
series of chipsets. Not only do the i875/i865 chipsets represent a huge technological leap compared
to their predecessors, but the performance gap between the pair of recent chipsets is significantly
less than it was between the i850E and i845 family.
There is a clear trend in PC hardware towards parallel processes, epitomised by Intel's Hyper-
Threading technology. However, there are other examples of where performing several tasks at the
same time is preferable to carrying out a single task quickly. Hence the increasing popularity of small
RAID arrays and now the trend towards dual-channel memory subsystems.
Currently, there are two different strategies being employed in dual-channel memory controllers, one
in which where each memory bank has its own memory channel and an arbiter distributes the load
between them and the other to actually create a wider memory channel, thereby "doubling up" on
standard DDR's 64-bit data paths. In common with the i875P chipset, the i865's Memory Controller
Hub employs the latter, the same conditions for dual-channel operation also applying.
The i865 memory controller is the same as that used by the i875P chipset, supporting:
• Hyper Threading
• Dual 64-bit DDR memory channels
• Communication Streaming Architecture bus for gigabit Ethernet
and capable of being paired with either the ICH5 or ICH5R chip - which handles things like the
10/100 Ethernet interface, 6-channel AC97 audio interface, USB 2.0, the PCI bus, etc., to provide the
following additional features:
• 8 USB 2.0 ports
• Dual independent Serial ATA ports
The ICH5R also provides software RAID for Serial ATA drives.
The upshot is that - unlike the i875P - i865 chipsets are available in three different versions:
• i865P: supports DDR266 and DDR333 memory only and doesn't support the 800MHz FSB.
• i865PE: as per i865P, plus 800MHz FSB and DDR400 memory support.
• i865G: as per i865PE, plus Intel's integrated graphics core.
Bài giảng KTSC Máy tính H.V.Hà
73
While the i865G's graphics core is the same as was featured on the i845G chipset, its
performance will be faster, due both to a faster memory subsystem and a higher working frequency
of the graphics core itself.
The following table compares a number of major characteristics of the i865P chipset with a
selection of Intel's other recent Hyper-Threading chipset offerings:
i865PE i875P E7205 i845PE i850E
Processor Pentium 4 Pentium 4 Pentium 4 Pentium 4 Celeron
Pentium 4
Celeron
System Bus
(MHz) 800/533/400 800/533/400 533/400 533/400 533/400
Memory Modules 4 DIMMs 4 DIMMs 4 DIMMs
2 double-
sided
DDR DIMMs
4 RIMMs
Memory Type
Dual-Channel
DDR
400/333/266
SDRAM
Dual-Channel
DDR
400/333/266
SDRAM
unbuffered only
x72 or x64
DIMMs
DDR SDRAM
DDR 333/266
PC1066
PC800-40
PC800-45
RDRAM
FSB/Memory
Configurations
800/400
800/333
533/333
533/266
400/333
400/266
800/400
800/333
533/333
533/266
533/266
400/200
533/333
533/266
400/266
533/PC1066
533/PC800-40
400/PC800-45
400/PC800-40
Peak Memory
Bandwidth 6.4GBps 6.4GBps 4.2GBps 2.7GBps 4.2GBps
Error Correction N/A ECC ECC N/A ECC/Non-
Bài giảng KTSC Máy tính H.V.Hà
74
ECC
Graphics
Interface AGP 8x AGP 8x AGP 8x AGP 4x AGP 4x
Serial ATA 2 ports ATA 150
2 ports
ATA 150 N/A N/A N/A
USB
8 ports
Hi-Speed
USB 2.0
8 ports
Hi-Speed
USB 2.0
6 ports
Hi-Speed
USB 2.0
6 ports
Hi-Speed
USB 2.0
4 ports
USB 1.1
Intel 925X PCI Express chipset
In the summer of...