About RAM (Random Access Memory)

RAM Memory TechnologyMemory Types In order to enable computers to work faster, there are several types of memory available today. Within a single computer there is no longer just one type of memory. Because the types of memory relate to speed, it is important to understand the differences when comparing the components of a computer.SIMM (Single In-line Memory Modules)SIMMs are used to store a single row of DRAM, EDO or BEDO chips where the module is soldered onto a PCB. One SIMM can contain several chips. When you add more memory to a computer, most likely you are adding a SIMM.The first SIMMs transferred 8 bits of data at a time and contained 30 pins. When CPU's began to read 32-bit chunks, a wider SIMM was developed and contained 72 pins.72 pin SIMMS are 3/4" longer than 30 pin SIMMs and have a notch in the lower middle of the PCB. 72 pin SIMMs install at a slight angle.DIMM (Dual In-line Memory Modules)DIMMs allow the ability to have two rows of DRAM, EDO or BEDO chips. They are able to contain twice as much memory on the same size circuit board. DIMMs contain 168 pins and transfer data in 64 bit chunks.DIMMs install straight up and down and have two notches on the bottom of the PCB.SODIMM (Small Outline DIMM)SO DIMMs are commonly used in notebooks and are smaller than normal DIMMs. There are two types of SO DIMMs. Either 72 pins and a transfer rate of 32 bits or 144 pins with a transfer rate of 64 bits.
RDRAM - RIMMRambus, Inc, in conjunction with Intel has created new technology, Direct RDRAM, to increase the access speed for memory. RIMMs appeared on motherboards sometime during 1999. The in-line memory modules are called RIMMs. They have 184 pins and provide 1.6 GB per second of peak bandwidth in 16 bit chunks. As chip speed gets faster, so does the access to memory and the amount of heat produced. An aluminum sheath, called a heat spreader, covers the module to protect the chips from overheating.SO RIMMSimilar in appearance to a SODIMM and uses Rambus technology.TechnologyDRAM (Dynamic Random Access Memory)One of the most common types of computer memory (RAM). It can only hold data for a short period of time and must be refreshed periodically. DRAMs are measured by storage capability and access time.Storage is rated in megabytes (8 MB, 16 MB, etc). Access time is rated in nanoseconds (60ns, 70ns, 80ns, etc) and represents the amount of time to save or return information. With a 60ns DRAM, it would require 60 billionths of a second to save or return information. The lower the nanospeed, the faster the memory operates. DRAM chips require two CPU wait states for each execution. Can only execute either a read or write operation at one time. FPM (Fast Page Mode)At one time, this was the most common and was often just referred to as DRAM. It offered faster access to data located within the same row. EDO (Extended Data Out)Newer than DRAM (1995) and requires only one CPU wait state. You can gain a 10 to 15% improvement in performance with EDO memory.BEDO (Burst Extended Data Out)A step up from the EDO chips. It requires zero wait states and provides at least another 13 percent increase in performance.SDRAM (Static RAM)Introduced in late 1996, retains memory and does not require refreshing. It synchronizes itself with the timing of the CPU. It also takes advantage of interleaving and burst mode functions. SDRAM is faster and more expensive than DRAM. It comes in speeds of 66, 100, 133, 200, and 266MHz.DDR SDRAM (Double Data Rate Synchronous DRAM)Allows transactions on both the rising and falling edges of the clock cycle. It has a bus clock speed of 100MHz and will yield an effective data transfer rate of 200MHz.
Check this site for more information about DDR Memory RAM
Direct RambusExtraordinarily fast. By using doubled clocked provides a transfer rate up to 1.6GBs yielding a 800MHz speed over a narrow 16 bit bus.Cache RAMThis is where SRAM is used for storing information required by the CPU. It is in kilobyte sizes of 128KB, 256KB, etc.Other Memory TypesVRAM (Video RAM)VRAM is a video version of FPM and is most often used in video accelerator cards. Because it has two ports, It provides the extra benefit over DRAM of being able to execute simultaneous read/write operations at the same time. One channel is used to refresh the screen and the other manages image changes. VRAM tends to be more expensive.Flash MemoryThis is a solid-state, nonvolatile, rewritable memory that functions like RAM and a hard disk combined. If power is lost, all data remains in memory. Because of its high speed, durability, and low voltage requirements, it is ideal for digital cameras, cell phones, printers, handheld computers, pagers and audio recorders.Shadow RAMWhen your computer starts up (boots), minimal instructions for performing the startup procedures and video controls are stored in ROM (Read Only Memory) in what is commonly called BIOS. ROM executes slowly. Shadow RAM allows for the capability of moving selected parts of the BIOS code from ROM to the faster RAM memory.

Virtual Memory and its influences on performance
While virtual memory makes it possible for computers to more easily handle larger and more complex applications, as with any powerful tool, it comes at a price. The price in this case is one of performance — a virtual memory operating system has a lot more to do than an operating system that is not capable of virtual memory. This means that performance will never be as good with virtual memory than with the same application that is 100% memory-resident.
However, this is no reason to throw up one's hands and give up. The benefits of virtual memory are too great to do that. And, with a bit of effort, good performance is possible. The thing that must be done is to look at the system resources that are impacted by heavy use of the virtual memory subsystem.
Worst Case Performance Scenario
For a moment, take what you have read earlier, and consider what system resources are used by extremely heavy page fault and swapping activity:
· RAM -- It stands to reason that available RAM will be low (otherwise there would be no need to page fault or swap).
Try this site for recommendations on DDR and SDRAM Memory Upgrades
· Disk -- While disk space would not be impacted, I/O bandwidth would be.
· CPU -- The CPU will be expending cycles doing the necessary processing to support memory management and setting up the necessary I/O operations for paging and swapping.
The interrelated nature of these loads makes it easy to see how resource shortages can lead to severe performance problems. All it takes is:
· A system with too little RAM
· Heavy page fault activity
· A system running near its limit in terms of CPU or disk I/O
At this point, the system will be thrashing, with performance rapidly decreasing.
Best Case Performance Scenario
At best, system performance will present a minimal additional load to a well-configured system:
· RAM -- Sufficient RAM for all working sets with enough left over to handle any page faults
· Disk -- Because of the limited page fault activity, disk I/O bandwidth would be minimally impacted
· CPU -- The majority of CPU cycles will be dedicated to actually running applications, instead of memory management
From this, the overall point to keep in mind is that the performance impact of virtual memory is minimal when it is used as little as possible. This means that the primary determinant of good virtual memory subsystem performance is having enough RAM.

Determining your Computer RAM Type
Currently the cost for adding additional memory is very low. Installation of memory is also fairly simple. It does not require any reconfiguration. The difficult part is determining what type of memory you need.
Type Socket Amount
More information on memory determination...Looking Inside Check the Manual Identification
Type
FPM – Fast Page - If you have a 486, you probably have FPM
EDO – Extended Data Out - If you have an early Pentium system, you probably have EDO
SDRAM - If you have a Pentium or Celeron system purchased in 1999, you probably have SDRAM
Sockets
Memory modules plug into a socket on the motherboard. There are three socket types.
SIMM – 30 pin – 3 inches in length
SIMM – 72 pin – 4 inches in length
DIMM – 168 pin – 5 inches in length
Most older 486 machines will use 30 pin modules. Later model 486 and Pentium machines will probably use 72 pin modules. More recent Pentium machines may have 168 pin.
Amount
Memory sizes increase by the power of 2. This results in sizes of 1, 2, 4, 8, 16, 32, 64, 128, 256 MBs.
On some older 486 machines, one memory module can be added at a time.
On most Pentium machines, modules must be added in pairs.
Each pair must be of the same size.
SDRAM modules can be added one at a time.
For example, if you have 8 MBs of memory on a Pentium, you have two 4 MB modules. To increase to 16 MBs, you need to add two more 4 MB modules. To increase to 24 MBs, you need to add two 8 MB modules.
Looking Inside
Now that you know the parameters, how do you determine which type you need? Looking inside the computer will not provide all of the information. It will confirm how many modules you currently have. You can also confirm the type and quantity of open sockets. If you only have four sockets and each socket contains a module, you will have to replace some of the existing memory modules.
Check the Manual
The other place to find the correct information is your owner’s manual. The manufacturer should have listed the type of memory required. You will need to determine the parity and speed.
Identification
Now that you have the necessary information, you find an ad for memory and still you may not be able to determine which modules you need. Why? Because the computer industry thrives on confusion and abbreviations. Here’s how to interpret the coding scheme.
30 pin modules
For 30 pin modules you will see something like
1 x 9-60
4 x 9-70
4 x 8-70
The first number is the size in MB’s. In our example this would be 1MB or 4MB.
The second number represents parity. The value 9 represents parity and 8 represents non-parity. (Of course that makes a lot of sense!) The 9 or 8 also identifies that it is a 30 pin module.
The third value represents the speed.
72 pin modules
For 72 pin modules you will see something like
1 x 32-60
2 x 32-70
4 x 36-60
8 x 36-70
Just like the 30 pin modules, the first value represents the size, EXCEPT it only represents ¼ of the total memory size. Don’t ask why, just accept it. So the value of 4 represents a 16 MB (4 x 4) module. A value of 8 represents a 32 MB (4 x 8) module.
The second value, again just like the 30 pin, represents parity and the number of pins. 36 is used for parity and 32 for non-parity. You aren’t asking why again, are you?
The third value represents the speed, the same as the 30 pin.

Why More RAM is Better ?
Has your old computer lost its get up and go? Or perhaps you've just invested in a brand spankin' new PC and you're thinking life is good… until your son tries his role-playing game over the Net, or you want to open four applications at once. You find that the animation just isn't quick enough, and neither is your multitasking. "But I have a new computer," you say. "It should be lightning fast!" Just because you have the latest, doesn't mean it's the greatest — in terms of performance. Good news! Help is easy and relatively inexpensive: upgrade the memory.
Upgrading your computer's memory (RAM) is one of the quickest, most efficient and most cost-effective ways to boost performance. Many new computers come with only a bare minimum of memory installed. Adding more RAM can add more zip to your system. And installation is not that complicated. Sometimes getting the case off takes more time than installing the actual RAM itself.
How much memory is enough? An average computer user is probably okay with the basic 128MB to 256MB of RAM. But as fast as technology changes, so will your need for additional memory. Just remember: more is better. 256MB is what most average users need. But if you're looking to make your processor really work for you — like for high-end applications, intense gaming and multimedia work — upgrade to even more RAM. You'll notice a significant performance gain all around.
Take a glance at what a memory upgrade can do for you Smoother multitaskingLike to have your charts and e-mail, too? Do you open several programs at the same time and switch between them frequently — and does your current PC moan and groan when you do? Then a memory upgrade is essential for smooth, effortless multitasking. It gives your computer an extra boost so it doesn't have to use the hard drive to manage data.
Faster Web surfingAre you a surf-aholic? If you like to spend countless hours on the Internet, but don't like when your system slows to a crawl, you'll want to add RAM. No matter how fast your Internet connection is, a memory upgrade can help your browser display pages faster. When your computer can store more data in RAM, it has to swap out less memory to the hard drive. Web sites use rotating banners, Flash and Shockwave animation, streaming audio and other plug-ins as dazzling effects to entice visitors. A computer memory upgrade can give your computer the zip it needs for today's browsing.
Enhanced printingDo you print large files like presentations with photos, clip art, graphics and charts? Are you tired of your pokey printer? A printing bottleneck can be fixed easily with a simple memory upgrade. And the boost in performance can have a big impact on productivity, especially in a networked environment where several PCs may be sharing one printer.A printer memory upgrade effects both quality and speed. The quality will improve because additional memory allows you to print better at higher resolutions. And you'll be able to print faster because a printer buffers (or holds data temporarily) part of a print job before actually printing. The more memory you have the more that can be buffered, and the faster you will print. (Note: Not all printers are upgradable. Check your owner's manual for details.)
More efficient video editingIf the video-editing bug has bitten, you'll want to add RAM. Editing is fun — or can be if it's not too slow. Because video files are very large, you'll not only need a big hard drive to store the file, but a quick processor and lots of RAM help speed things up. Video editing software like iMovie and Adobe Premiere typically recommend 64MB of RAM, but once again, more is better. 256MB or more should have you editing without waiting for your computer's hard drive to catch up.
Optimized Windows XP processingMicrosoft's Windows XP is power-packed with enhanced multimedia, gaming and Internet capabilities. It's touted as faster, easier to use and better for remote computing. What's not to like? So take full advantage of all the incredible features by optimizing the performance with a RAM upgrade.
Windows XP ready-labeled computers must meet minimum hardware requirements for the software. But meeting these requirements does not ensure the system is configured for maximum performance with Windows XP. Typically, just meeting minimum requirements for software means minimum performance. Like before: more is better. You'll need at least 128MB, but 256MB is recommended. For the optimal Windows XP experience load up on RAM.
Spectacular gamingA new graphics card is nice, but it isn't enough for today's cutting edge gaming. Revolutionize your 3D gaming experience by adding more memory. Added RAM supports color at higher resolutions and gives you the power for enhanced 3D rendering, with amazing character realism and texture versatility. Enjoy crisper, brighter images and excitingly fast 3D video and animation for a powerful, virtually real gaming experience.
Enhanced multimedia presentationsIntense graphics use and memory-laden programs, such as multimedia, publishing and graphics arts, demand more RAM for the optimal computing experience. Flash and ROM take up a lot of space. You're going to need at least 128MB, with 256MB or more needed for best performance. Once again, more is better. The applications respond much quicker with faster image drawing.
Efficient networkingA memory upgrade is essential for efficient networking. The server as well as individual PCs can be upgraded to lend more benefits for everyone.

How Much Memory Do I Need ? The answer really depends on how much and for what your system is used. Upgrading is easy and cost effective. RAM is used every time you open an application, download, play a game or simply turn on your computer. Additionally if you work with or plan to work with digital audio and video more ram is a necessity.
Novice User / AdministrativeIf you use your computer to send and receive email, do a little word processing, and are starting to surf the Web, you can get by with 64MB. However, you would benefit from going to at least 128MB of memory.
Basic UserIf you are spending more time surfing the internet, sending and receiving email, and doing word processing along with other applications, you can get by with 128MB, but would benefit from going to 256MB.
Professional / Feel the need for Speed!If you are running multiple business applications, want to play the newer video games and/or work with graphics, you can get by with 256MB, but your computer speed would benefit greatly by having 512MB.
Advanced ProfessionalIf you work with high-end graphics, CAD software, digital images, or video, you can get by with 256MB, but would benefit greatly by installing 512MB of memory or more. Right now our 512MB memory modules are available at incredibly low prices.
Graphics Design ProfessionalIf you are, or plan to be, a professional graphics designer, use CAD or modeling software, digital images or video, you can get by with 512MB, but would benefit from going to 1GB of memory or more.
Gaming rig??
Ahhhh. Here's the point of all this tech talk. For a gaming rig, how much is enough? Well, before this article, I would have said, anything over 128Mb. We'll see if that's my opinion at the end, although I do recommend instead of skipping to the end, you read what I have to say, because there's some twists to this article that might interest you.
Test System
Below is the system that was used in this article, along with any other important information.
Intel Pentium 3 800MhzHercules Prophet SDR (GeForce 256)Abit BX6 Rv. 2.0 MotherboardMicrosoft Windows 2000 SP2 Operating SystemTest Programs: Quake 3 Arena, 3Dmark 2000
Let me explain some things. I believe the Windows 9x series is now defunct. Windows XP is the future, and the Windows 2000 core is the closest thing I have to to XP, so that's why 2000 was used in this review. Also, Windows 2000 has the best memory handling of all the current Windows OS's. Add in there: total stability, and supreme control over the OS, and you've got all my reasons. The reason Quake 3 is used, is because it's a very taxing program on a system like mine, and it's very easy to benchmark. 3Dmark 2000 was used because 2001 is made for next-gen video cards, and by using 2000 there's more discrepancy between results, making them easier to apply to an article.

How Much RAM Is Enough ?
The answer to this question is a straightforward...it depends. It depends upon what you are using your computer for and what operating system you are using, to take the two most obvious factors. If you are using Adobe Photoshop or doing video editing all the time, and want to be able to run office applications, and surf, and do email, all at once - well, then you may need a fair amount of memory. If you are a typical home user and mostly use your computer for email, surfing, a word processor or spreadsheet, and the occasional game, then you won't need quite as much. In terms of how it affects you, the end user, having the right amount of memory = faster computer.
Here's some general guidelines for the typical home user (note MB = Megabyte, the main unit in terms of which memory is sold; the higher the number, the more memory you have):
Windows 95 - Seems to be happy with 64 MB. Anything over doesn't get you much performance increase, but if you have anything less, I'd seriously consider getting more memory. The benefit can be quite substantial.
Windows 98/Me - Seems to be happy with 128 MB. Works ok with 64 MB, but you will probably see a significant performance increase by going to 128. Anything over 128 generally doesn't get you much.
Windows NT (Workstation) - Seems to be happy with 128 MB for most things.
Windows NT (Server) - Can run with 128 MB, but more is better. Definitely consider getting 256 MB or more if this server is going to have a heavy demand on it.
Windows 2000 - At least 128 MB, and basically as much as you can throw at it. Seriously consider 256 MB or more if it's got a heavy demand on it.
Windows XP - Hard to say, but 256 MB minimum, and almost certainly would work better with more.
Operating System
Fresh Install Memory Usage
Recommended Memory Size
Installed System Memory
Microsoft Windows Vista Home Basic
554MB
512MB
1GB
Microsoft Windows Vista Home Premium
552MB
1GB
1GB
Microsoft Windows Vista Ultimate
541MB
1GB
1GB

Frequently asked Questions on Memory (FAQs)
What are the benefits of upgrading your computers memory?Upgrading your memory is typically the easiest and least expensive way to upgrade your computer for a significant boost in performance. The computer's RAM memory is its workspace, or where all of the instructions it needs to act on are stored temporarily. Think of the RAM as the desk you use to sort through your work. If the size of that desk is small, your efficiency is limited in comparison to a larger desk that allows you to work more effectively and efficiently. Similarly, a computer with more RAM can work more efficiently because it does not need to retrieve information from the hard disk drive as often. A memory upgrade is particularly helpful for users who work with large files, have more than one program open at one time, or use memory-intensive applications such as games or graphics and video editing software.
How do you know it's time for a memory upgrade?There are several signs indicating it may be time to upgrade your memory. If you see your mouse pointer turn into an hourglass for significant periods of time, if you hear your hard drive working, or if your computer seems to work more slowly than you expect, the reason is probably insufficient memory. When physical memory is insufficient, the system uses Hard Disk Space as memory. This is called "Virtual Memory". Since access time of Physical memory is in tens of NanoSeconds and Access time of Hard Disk is in MilliSeconds, the system slows down considerably.
DDR2 Memory Memory
DDR2 is the next-generation DDR memory technology which features faster speeds, higher data bandwidths, lower power consumption, and enhanced thermal performance.
Try this site for recommendations on DDR and DDR2 Memory UpgradesDDR2 Unbuffered DIMM ECC and Non-ECC ( 240pin)For PC and low end workstations Dimension approx. 5.25" x 1.18" (13.34cm x 2.99cm)
Registered ECC DIMMs ( 240 pin) For Server and high end workstations
Unbuffered DDR2 SODIMM ( 200pin)For Laptop and Cube PC
MicroDIMM( 214 pin)Micro-DIMM is a SO-DIMM with a smaller outline and thickness than standard SO-DIMMs. Therefore it is designed for sub-Notebooks applications which are mobile type, slim type and super light weight Notebooks.
Very small outline DIMM Densities: 256MB, 512MB, 1GB Based on Infineon's 512Mbit and 1Gb componentsSpeed: DDR2-400, DDR2-533
What is a DDR2 DIMM ?
A dual inline memory module (DIMM) consists of a number of memory components (usually black) that are attached to a printed circuit board (usually green). The gold pins on the bottom of the DIMM provide a connection between the module and a socket on a larger printed circuit board. The pins on the front and back of a DIMM are not connected to each other.

DDR2 memory modules are offered in two frequency range, 400MHz and 533MHz speeds (data rate) in 2004, and followed by 667MHz by Fall of 2005.

240-pin DIMMs are used to provide DDR2 SDRAM memory for desktop computers. Each 240-pin DIMM provides a 64-bit data path (72-bit for ECC or registered modules), so they are installed singly in 64-bit systems. Most DDR2 chipsets are expected to support dual-channel memory, effectively providing a 128-bit data pathDDR2 DIMM memory modules are not backward-compatible with DDR DIMM , due to incompatible pin configurations, core voltage, and memory chip technology. DDR2 modules are designed with a different "key" in the edge connector to prevent insertion into incompatible memory sockets such as DDR motherboard. A DDR2 SDRAM DIMM will not fit into a standard SDRAM DIMM socket or a DDR DIMM socket. DDR2 modules use a 1.8V power supply, providing a big power saving over the 2.5V DDR modules.

240-pin DIMMs are available in DDR2 PC2-4200 (DDR2-533) SDRAM or DDR2 PC2-3200 (DDR2-400) SDRAM. To use DDR2 memory, your system motherboard must have 240-pin DIMM slots and a DDR2-enabled chipset.

DDR2 Memory Chips DDR2 memory can no longer be made into TSOP chips, and are offered FBGA (Fine-pitch Ball Grid Array) chips.

Memory Classifications
Memory Speed are offered in 400, 533 & 667Mhz
Memory Chip classification are named : DDR2-400 , DDR2-533Mhz and DDR2-667Mhz
Module DIMM Classificiation are named : PC2-3200 or 400Mhz) , PC2-4200 or 533 mhz and PC2-533 or 667Mhz
Module Bandwidth : PC2-3200 = 3.2 Gb/s , PC2-4200= 4.2 Gb/s & PC2-5300= 10.6 Gb/s
DDR2 was designed to overcome many of the problems with DDR:

DDR2 versus DDR Modules DDR2 memory modules have basically the same dimensions as the DDR modules, but have different pin configurations, therefore DDR2 DIMM will not fit in the DDR memory slot.
The table compares the different types of modules for DDR and DDR2:

DDR2
DDR
Unbuffered DIMM
240pin 1.8V
184pin 2.5V
Registered DIMM
240pin 1.8V
184pin 2.5V
SODIMM
200pin 1.8V
200pin 2.5V
Mini Registered DIMM
244pin 1.8V
—
MicroDIMM
214pin 1.8V
172pin 2.5V
Because of different voltages and pin configurations, DDR2 modules will have a different "key" or notch in their connector to prevent them from being plugged into an incompatible socket. DDR2 memory modules will only fit in systems and motherboards designed to specifically support DDR2 memory. The number of black components on a 240-pin DIMM may vary, but they always have 120 pins on the front and 120 pins on the back.While 240-pin DDR2 DIMMs, 184-pin DDR DIMMs and 168-pin DIMMs are approximately the same size, 240-pin DIMMs and 184-pin DIMMs have only one notch within the row of pins.
DDR3 Memory Modules Launched
Intel Bearlake P35 based desktop motherboards are released for the very first time which support DDR3 memory. While these motherboards will feature the latest and greatest Intel P35 chipsets they also happen to be the first desktop platform that utilizes DDR3 memory modules. For those that don't know DDR3 is the next generation of Double Data Rate (DDR) Synchronous Dynamic Random Access Memory (SDRAM). DDR3 memory modules are an improvement of DDR and DDR2 memory technology and will deliver higher clock frequencies, lower power consumption and as a result lower heat dissipation. When DDR3 is launched the frequencies will be at 1066Mhz and 1333Mhz, with 1600MHz and beyond out in the distance.
For those that recall the transition from DDR1 to DDR2, the move from DDR2 to DDR3 will be much the same. It will take years for DDR3 to become main stream with many predicting that it will take the industry till 2009 to fully moved over to the new memory form factor. Those with DDR2 motherboard have nothing to worry about as DDR2 production will continue with improved parts still on the drawing boards.
About three years ago DDR2 memory first appeared on the desktop PC scene. It would be impossible to say it burst on the scene since it was introduced with the unimpressive Intel NetBurst processors. In that market DDR2 was more like a trickle since it was mainly a curiosity for a processor that was running a distant second place to the leading AMD Athlon chips, which were still powered by DDR memory.
DDR2 finally became the universal standard last May/June when AMD switched to DDR2 on their new AM2 platform and Intel introduced Core 2 Duo, the new CPU performance leader. Core 2 Duo resided on socket 775, which also was fed by DDR2. While it sometimes seems like centuries ago, it is worth remembering that Intel Core 2 Duo regained the CPU performance crown less than a year ago, and the two years prior to that all the fastest systems used AMD Athlon 64/X2/FX processors.
Performance of DDR2 on the new platforms in July of last year. AM2 provided better bandwidth with DDR2, but the better AM2 bandwidth did not translate into better performance. Since Core 2 Duo was faster at the same timings, it appeared the Intel Core 2 Duo architecture was not particularly bandwidth hungry and that it made very good use of the DDR2 bandwidth that was available with the chipset memory controller.
Since last May/June DDR2 has finally turned the market, and it has made some remarkable transformations along the way. The early 5-5-5 timings at the official DDR2-800 speed have since been replaced by several high performance memories capable of 3-3-3 timings at DDR2-800. The best memory at DDR2-1066 can now operate at 4-4-3 timings, and the fastest DDR2 is now around DDR2-1266 and still getting faster.
Perhaps even more remarkable, in the last year DDR2 memory prices have dropped to half of what they once were (sometimes more), and today DDR2 is often cheaper than the DDR memory it replaced. Compared to the very expensive prices at launch and into the holiday buying season we see DDR2 is now the memory price standard in the desktop computer market.