The memory controller, the interface between the CPU and system memory, is part of the Northbridge portion of the motherboard chipset. (See "Your PC's Second Most Important Silicon" for an introduction to chipsets -- Ed.) Besides handling data flow to and from the processor, the memory controller also governs the system's support for different types (such as SDRAM, DDR, or RDRAM) and speeds (such as DDR333 or PC1066) of memory, along with the maximum module size and installable memory ceiling. In short, it determines the type, size, and overall performance of a PC's memory subsystem.
There are many memory controller designs, each with its own pros and cons. The standard configuration for most of today's PCs is a single-channel architecture, like that of the Intel 845 line; VIA KT333, KT400 and P4X400; and SiS 645DX and 648, among others. In addition to high availability, this design has the advantages of low cost and excellent memory compatibility and flexibility.
On the negative side, a single-channel memory controller becomes a performance bottleneck when it can't keep up with the CPU bus, leaving the processor to waste clock cycles with nothing to process. This is a problem in all low-priced Pentium 4 chipsets, as Intel's flagship processors' 533MHz front-side bus can easily overwhelm even a 400MHz DDR400 memory pipeline.
The appetite gap even affects relatively high-end chipsets like Intel's 845PE, which supports the latest Pentium 4 chips and Hyper-Threading technology, but is limited to the 333MHz memory speed of DDR333 (a.k.a. PC2700). The latter type of memory is a great match for a 333MHz-bus Athlon XP, but pairing it with a 533MHz-bus Pentium 4 is like using a Porsche to drive in city traffic.
Dual Channel to the Rescue
To cure the bandwidth backup, chipset manufacturers have been quick to embrace the benefits of dual-channel memory architecture. Although there are many differences between models, the basic concept is as simple as opening a second checkout line at the supermarket -- adding a second memory channel for theoretically double the bandwidth. If a single channel of DDR266 memory supplies 2.13GB/sec of bandwidth, then naturally a dual-channel memory controller (using two modules or sticks of DDR266) can enjoy 4.3GB/sec of bandwidth.
(Before going any further, let's be sure to differentiate between dual-channel memory controller designs and the dual-data-rate (DDR) memory that many of them use. The acronym DDR refers to RAM that transfers data on both the rising and falling edges of each clock cycle [see "Making Sense of System Memory" -- Ed.], thereby turning 133MHz SDRAM into 266MHz DDR SDRAM. A dual-channel DDR controller implements two separate memory channels, each compatible with DDR memory. One is a memory design and the other is a chipset design.)
Sometimes the simplest solution can be the most elegant, and this old axiom certainly applies to dual-channel memory controllers. The concept is almost one of "reduce, recycle, reuse," in that it turns older, slower, and cheaper memory into an up-to-date speed demon by adding a second, parallel memory pathway. Instead of having to ratchet up memory clock speeds and creating timing and stability issues (e.g., waiting for someone to invent DDR533), dual-channel controllers simply take what's widely available (e.g., DDR266) and double it.
you are not right..the most important part of the motherboard is the north bridge the only part that will determine if it will support dual channel
i am not giving him wrong information and please do not state information you thinkn is correct with out proof the cpu has nothign to do with determining if the setup will run dual channel
my point was obviously much above your head with the tbird i was speaking on a timeline that the cpu can run a dual channel setup when the processor was manufactured much before chipsets with dual channel support can about
lol nice try thought i must say, i believe it is your ego getting int he way...just because you do not knwo the proper components or there exact purpose in a computer doesnt mean anything to me....me and joel owned extreme tech copmuters and i knwo for a fact that the knowledge i have and put forth is correct and in his best interest..please give up and if you have nothing to say to help him stop...pwn3d
excuse my typing im in a bit of a hurry and have no interest in trying to correct it
Josh
There are many memory controller designs, each with its own pros and cons. The standard configuration for most of today's PCs is a single-channel architecture, like that of the Intel 845 line; VIA KT333, KT400 and P4X400; and SiS 645DX and 648, among others. In addition to high availability, this design has the advantages of low cost and excellent memory compatibility and flexibility.
On the negative side, a single-channel memory controller becomes a performance bottleneck when it can't keep up with the CPU bus, leaving the processor to waste clock cycles with nothing to process. This is a problem in all low-priced Pentium 4 chipsets, as Intel's flagship processors' 533MHz front-side bus can easily overwhelm even a 400MHz DDR400 memory pipeline.
The appetite gap even affects relatively high-end chipsets like Intel's 845PE, which supports the latest Pentium 4 chips and Hyper-Threading technology, but is limited to the 333MHz memory speed of DDR333 (a.k.a. PC2700). The latter type of memory is a great match for a 333MHz-bus Athlon XP, but pairing it with a 533MHz-bus Pentium 4 is like using a Porsche to drive in city traffic.
Dual Channel to the Rescue
To cure the bandwidth backup, chipset manufacturers have been quick to embrace the benefits of dual-channel memory architecture. Although there are many differences between models, the basic concept is as simple as opening a second checkout line at the supermarket -- adding a second memory channel for theoretically double the bandwidth. If a single channel of DDR266 memory supplies 2.13GB/sec of bandwidth, then naturally a dual-channel memory controller (using two modules or sticks of DDR266) can enjoy 4.3GB/sec of bandwidth.
(Before going any further, let's be sure to differentiate between dual-channel memory controller designs and the dual-data-rate (DDR) memory that many of them use. The acronym DDR refers to RAM that transfers data on both the rising and falling edges of each clock cycle [see "Making Sense of System Memory" -- Ed.], thereby turning 133MHz SDRAM into 266MHz DDR SDRAM. A dual-channel DDR controller implements two separate memory channels, each compatible with DDR memory. One is a memory design and the other is a chipset design.)
Sometimes the simplest solution can be the most elegant, and this old axiom certainly applies to dual-channel memory controllers. The concept is almost one of "reduce, recycle, reuse," in that it turns older, slower, and cheaper memory into an up-to-date speed demon by adding a second, parallel memory pathway. Instead of having to ratchet up memory clock speeds and creating timing and stability issues (e.g., waiting for someone to invent DDR533), dual-channel controllers simply take what's widely available (e.g., DDR266) and double it.
you are not right..the most important part of the motherboard is the north bridge the only part that will determine if it will support dual channel
i am not giving him wrong information and please do not state information you thinkn is correct with out proof the cpu has nothign to do with determining if the setup will run dual channel
my point was obviously much above your head with the tbird i was speaking on a timeline that the cpu can run a dual channel setup when the processor was manufactured much before chipsets with dual channel support can about
lol nice try thought i must say, i believe it is your ego getting int he way...just because you do not knwo the proper components or there exact purpose in a computer doesnt mean anything to me....me and joel owned extreme tech copmuters and i knwo for a fact that the knowledge i have and put forth is correct and in his best interest..please give up and if you have nothing to say to help him stop...pwn3d
excuse my typing im in a bit of a hurry and have no interest in trying to correct it
Josh
