registered/unbuffered RAM?
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ailevation
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:thumbs: Registered RAM is better, that is all I know.
Asus
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Unbuffered is what you will most likely need. Registered RAM adds some latency.
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The registering or buffering can take place in either the memory controller or the memory module. But not both. You cannot use Registered Ram in mainboards where the memory controller registers the data and you cannot use Unbuffered memory in mainboards where Registered RAM is needed.
Basicly, each stick of Registered RAM registers the data in it's own stick.
When the memory controller registers the data, you use unbuffered memory. There are limitations when the memory controller registers the data. When too much memory is used, the P4's memory controller looses latency while the Athlon's memory controller looses speed. Link
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The registering or buffering can take place in either the memory controller or the memory module. But not both. You cannot use Registered Ram in mainboards where the memory controller registers the data and you cannot use Unbuffered memory in mainboards where Registered RAM is needed.
Basicly, each stick of Registered RAM registers the data in it's own stick.
When the memory controller registers the data, you use unbuffered memory. There are limitations when the memory controller registers the data. When too much memory is used, the P4's memory controller looses latency while the Athlon's memory controller looses speed. Link
Why Registered RAM?
Servers and mission critical systems is the explanation given most as to why to use Registered RAM.
Why?
Often this explanation is used as a "because I said so" statement and left at that. It has always been quoted but never really explained. Enthusiasts rejoice at the introduction of Socket 939 because the processor does not require Registered RAM as did its Socket 940 predecessor. Registered RAM is more of a specialty item compared to unbuffered "normal" RAM and as such it is more expensive and the choices fewer. First assumption by anyone would be to put Socket 940 on the road to obsolescence with the introduction of the Socket 939 processor.
Let's begin with the memory itself. Registered refers to the registers onboard the RAM which hold data for one clock cycle before moving the data to the motherboard. This increases the reliability of the data. The "hold" for one clock cycle explains why Registered RAM is slower than unbuffered memory. "Slower" is a relative term like one dragster is "slower" than the other. Both move pretty fast.
Registered RAM can also be ECC Registered RAM. The "ECC" stands for "Error Checking and Correction". Others use "Error-Correcting Code." In both cases it's the same built-in function of the RAM to automatically correct errors in data as it passes in and out of the RAM. These errors are known as "soft errors" or SER.
The reason for soft errors is incredulous but true. At the chip level a soft error occurs when the radioactive atoms in the chip's material decay and release alpha particles into the chip. Those particles can "hit" a memory cell in the chip and force a change. As an example that memory cell may, at that time, be holding a binary code value of 1 and the particle collision may change it to a 0. Think of it like a billiards table where the cue ball strikes another ball knocking it out of position.
Chip level errors are extremely rare and there's no worry of these particles bouncing wildly about ripping tiny holes in everything including the RAM, the motherboard, your legs, etc. These collisions are on the atomic scale and it's more the physics of electrical interaction than anything else. RAM technology has increased so much making chip level errors extremely rare.
System level soft errors occur because of noise interference. This noise isn't a stereo that's too loud but "noise" of unwanted radiation from other components. Think of it like trying to tune in a radio station. The clear signal is what is desired but the static is the unwanted noise. That noise interferes with the ability to hear the song clearly. The song "corrupts" and words may be misheard or not heard at all. In the case of memory the data passing to and from the ram is the song and the noise "corrupts" the data. System level soft errors typically occur as the data is traveling to and from the RAM on the data bus but not within the RAM chips themselves.
How often chip level or system level soft errors occur is most difficult to pin down. These soft errors occur randomly and this randomness if further compounded by the variable of other system components and environment situations. The PSU may not have enough shielding. Someone may have parked a speaker next to the PC case. The cat may have rubbed up against the PC and discharged static electricity. Think on the microscopic level too. Did that trace on the motherboard leak a weak electrical signal and interfere with the trace next to it?
The variables never end and it's safe to say that the odds are largely against soft errors but they do happen.
Stand alone systems typically use unbuffered memory. That is to say it's not ECC Registered memory. On average the home PC isn't being taxed as much compared to a server nor does it handle as much data over an extended period of time. A server is designed to "serve" many users; tens, hundreds or thousands at a time. This load means a tremendous amount of data is being passed about and, at times, during a 24/7 period. The odds of a soft error occurring are much higher. ECC Registered RAM will correct these errors thus everybody gets what they came for instead of glitches, crashes or BSODs.
Remember that any computer that is accessed by one or more users can be thought of as a "server." This includes that PC that stores MP3s that are played back through the home network or a LAN party game server and so on right up to those corporate servers which are eternally blamed for the email not working.
A workstation is also another PC that may benefit from ECC Registered RAM. 3D programs such as Autocad, 3D Studio Max and Softimage manipulate a tremendous amount of data. If that data corrupts then frequent crashes result in downtime and that means lost time and money. 3D programs and even some 2D programs such as Adobe After Effects can render or "put together" a finished project taking a long period of time. This period may be over an hour or a day but the longer the duration increases the odds of an error. The last thing any graphic artists wants to see is a glitch half way through an 8 hour render. ECC Registered RAM is better suited to avoid those occurrences.
It is true that Registered RAM is slower than unbuffered memory. The reason is because Registered RAM modules have buffers on the address and control lines. These buffers along with the clock driver chip act like signal boosters. In layman's terms data has a very weak electrical signal. If it had a stronger electrical signal then it could result in leakage and then it's back to the soft error problem. That data has to reach a lot of places in a PC with a lot of memory such as a server which may have greater than 4 GB of RAM installed. The electrical "oomph" of the data isn't enough to travel to all the places in the ram module without degridation...aka errors. The buffers give those signals a helping hand. The buffer and clock driver operation requires more time to "do its thing." The time needed can be measured in nanoseconds and it would be difficult for the average user to tell the difference in the "feel" and "speed" of the PC given two matching setups; the only difference being one used unbuffered memory and the other used ECC Registered. Benchmarks would show a difference but, as will be seen later in this article, that difference is very small.
That's an extremely simplified view but it is adequate for this level of explanation. This is a reason why motherboards with 2 and 3 DIMMS are common. Less DIMMS do cut down on the overall cost of manufacturing the board but a move to higher memory capability may cross that threshold between requiring Registered memory instead of unbuffered.
That threshold is changing as memory technology and dependability increases. Unbuffered memory modules at the 512 and 1 GB level are common which means that a system with a whopping 2 GB of unbuffered memory is easily attainable. Push to the 3, 4 or 8 GB level and it's safer to use ECC Registered memory. It used to be less a year or two ago and it will be more in years to come. Technology marches on.
As a final point of conjecture it's important to know that Registered modules can be buffered and unbuffered. The difference is the inclusion of buffers hence the term. ECC also is an additional feature. For the most part the most common types of memory are ECC Registered Buffered memory, ECC unbuffered and "normal" unbuffered memory (non-parity).
So why use Registered RAM?
Consider using Registered RAM if the goal is to have a PC:
* That has a large amount of memory. Start considering it at the 3 GB level.
* That serves another regardless of the amount of users.
* That supports 2D or 3D data intensive programs especially if those programs can take a long period of time to complete a task.
* That is used wherever data integrity is of critical importance to the end user.
So now it's clearer to see that a Socket 939 FX-53 processor would make for a formidable gaming system but a Socket 940 FX-53 would make for a very powerful single processor workstation. Each has their useful niche and, when all things are considered. The choice must be made between saving on purchase of a system that uses unbuffered memory to only spend that savings in downtime and re-done projects. The variable of Opteron has not been introduced at this time.
-------------------
Taken from an amazing article here. http://www.short-media.com/review.php?r=247&p=2
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Servers and mission critical systems is the explanation given most as to why to use Registered RAM.
Why?
Often this explanation is used as a "because I said so" statement and left at that. It has always been quoted but never really explained. Enthusiasts rejoice at the introduction of Socket 939 because the processor does not require Registered RAM as did its Socket 940 predecessor. Registered RAM is more of a specialty item compared to unbuffered "normal" RAM and as such it is more expensive and the choices fewer. First assumption by anyone would be to put Socket 940 on the road to obsolescence with the introduction of the Socket 939 processor.
Let's begin with the memory itself. Registered refers to the registers onboard the RAM which hold data for one clock cycle before moving the data to the motherboard. This increases the reliability of the data. The "hold" for one clock cycle explains why Registered RAM is slower than unbuffered memory. "Slower" is a relative term like one dragster is "slower" than the other. Both move pretty fast.
Registered RAM can also be ECC Registered RAM. The "ECC" stands for "Error Checking and Correction". Others use "Error-Correcting Code." In both cases it's the same built-in function of the RAM to automatically correct errors in data as it passes in and out of the RAM. These errors are known as "soft errors" or SER.
The reason for soft errors is incredulous but true. At the chip level a soft error occurs when the radioactive atoms in the chip's material decay and release alpha particles into the chip. Those particles can "hit" a memory cell in the chip and force a change. As an example that memory cell may, at that time, be holding a binary code value of 1 and the particle collision may change it to a 0. Think of it like a billiards table where the cue ball strikes another ball knocking it out of position.
Chip level errors are extremely rare and there's no worry of these particles bouncing wildly about ripping tiny holes in everything including the RAM, the motherboard, your legs, etc. These collisions are on the atomic scale and it's more the physics of electrical interaction than anything else. RAM technology has increased so much making chip level errors extremely rare.
System level soft errors occur because of noise interference. This noise isn't a stereo that's too loud but "noise" of unwanted radiation from other components. Think of it like trying to tune in a radio station. The clear signal is what is desired but the static is the unwanted noise. That noise interferes with the ability to hear the song clearly. The song "corrupts" and words may be misheard or not heard at all. In the case of memory the data passing to and from the ram is the song and the noise "corrupts" the data. System level soft errors typically occur as the data is traveling to and from the RAM on the data bus but not within the RAM chips themselves.
How often chip level or system level soft errors occur is most difficult to pin down. These soft errors occur randomly and this randomness if further compounded by the variable of other system components and environment situations. The PSU may not have enough shielding. Someone may have parked a speaker next to the PC case. The cat may have rubbed up against the PC and discharged static electricity. Think on the microscopic level too. Did that trace on the motherboard leak a weak electrical signal and interfere with the trace next to it?
The variables never end and it's safe to say that the odds are largely against soft errors but they do happen.
Stand alone systems typically use unbuffered memory. That is to say it's not ECC Registered memory. On average the home PC isn't being taxed as much compared to a server nor does it handle as much data over an extended period of time. A server is designed to "serve" many users; tens, hundreds or thousands at a time. This load means a tremendous amount of data is being passed about and, at times, during a 24/7 period. The odds of a soft error occurring are much higher. ECC Registered RAM will correct these errors thus everybody gets what they came for instead of glitches, crashes or BSODs.
Remember that any computer that is accessed by one or more users can be thought of as a "server." This includes that PC that stores MP3s that are played back through the home network or a LAN party game server and so on right up to those corporate servers which are eternally blamed for the email not working.
A workstation is also another PC that may benefit from ECC Registered RAM. 3D programs such as Autocad, 3D Studio Max and Softimage manipulate a tremendous amount of data. If that data corrupts then frequent crashes result in downtime and that means lost time and money. 3D programs and even some 2D programs such as Adobe After Effects can render or "put together" a finished project taking a long period of time. This period may be over an hour or a day but the longer the duration increases the odds of an error. The last thing any graphic artists wants to see is a glitch half way through an 8 hour render. ECC Registered RAM is better suited to avoid those occurrences.
It is true that Registered RAM is slower than unbuffered memory. The reason is because Registered RAM modules have buffers on the address and control lines. These buffers along with the clock driver chip act like signal boosters. In layman's terms data has a very weak electrical signal. If it had a stronger electrical signal then it could result in leakage and then it's back to the soft error problem. That data has to reach a lot of places in a PC with a lot of memory such as a server which may have greater than 4 GB of RAM installed. The electrical "oomph" of the data isn't enough to travel to all the places in the ram module without degridation...aka errors. The buffers give those signals a helping hand. The buffer and clock driver operation requires more time to "do its thing." The time needed can be measured in nanoseconds and it would be difficult for the average user to tell the difference in the "feel" and "speed" of the PC given two matching setups; the only difference being one used unbuffered memory and the other used ECC Registered. Benchmarks would show a difference but, as will be seen later in this article, that difference is very small.
That's an extremely simplified view but it is adequate for this level of explanation. This is a reason why motherboards with 2 and 3 DIMMS are common. Less DIMMS do cut down on the overall cost of manufacturing the board but a move to higher memory capability may cross that threshold between requiring Registered memory instead of unbuffered.
That threshold is changing as memory technology and dependability increases. Unbuffered memory modules at the 512 and 1 GB level are common which means that a system with a whopping 2 GB of unbuffered memory is easily attainable. Push to the 3, 4 or 8 GB level and it's safer to use ECC Registered memory. It used to be less a year or two ago and it will be more in years to come. Technology marches on.
As a final point of conjecture it's important to know that Registered modules can be buffered and unbuffered. The difference is the inclusion of buffers hence the term. ECC also is an additional feature. For the most part the most common types of memory are ECC Registered Buffered memory, ECC unbuffered and "normal" unbuffered memory (non-parity).
So why use Registered RAM?
Consider using Registered RAM if the goal is to have a PC:
* That has a large amount of memory. Start considering it at the 3 GB level.
* That serves another regardless of the amount of users.
* That supports 2D or 3D data intensive programs especially if those programs can take a long period of time to complete a task.
* That is used wherever data integrity is of critical importance to the end user.
So now it's clearer to see that a Socket 939 FX-53 processor would make for a formidable gaming system but a Socket 940 FX-53 would make for a very powerful single processor workstation. Each has their useful niche and, when all things are considered. The choice must be made between saving on purchase of a system that uses unbuffered memory to only spend that savings in downtime and re-done projects. The variable of Opteron has not been introduced at this time.
-------------------
Taken from an amazing article here. http://www.short-media.com/review.php?r=247&p=2
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