# pc2-5300 vs pc25300f



## brainfaded

I just bought 8Gb of pc2-5300f Ram. Unfortunately,it doesn't fit in the slots that previously held pc2-5300 Ram. So what I want to know is, does the 'f' make a difference? The model numbers for the Ram sticks are

Working- Ultra brand 2Gb "ULT40089" pc2-5300 DDR2 67MHz
Not working- Kingston Brand 4Gb "F51272F51LP" 2rx4 pc2-5300f


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## Tyree

pc2-5300f is ECC RAM most commonly used in Server Mobo's. Return it and get a matched pair of 2 X 2 GB (more than enough) PC5300 DDR2 667 Mhz Unbuffered Non-ECC RAM.


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## brainfaded

Thanks! That's exactly what I needed to know!


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## nomad360

so...what does the 'f' actually stand for? I've seen many different letters used in that spot on server ram, but I don't know what it means. Help?


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## cellar7

*Re: pc2-5300 vs pc2-5300f*

This is a great question and unfortunately there's not much information on the internet to clarify exactly what's different and why. There is no exact standard for designating what type of memory you're looking at although most manufacturers are in the same ballpark. Here are some of the suffixes found on some PC2 and other types of SDRAM depending on the manufacturer.

You may find an "R" or a "U" suffix on your memory. The R stands for registered (also called buffered) which improves data integrity but slows data processing slightly. This type of RAM is usually found on mission critical systems like servers. Memory that is non-registered (also called unbuffered) sometimes contain a U suffix for unbuffered. Unbuffered memory has slightly faster performance but is not as reliable as buffered memory for accurate data transfer.

Beyond buffered memory is Fully Buffered memory, which may be designated by an "F"or "FB" suffix and is physically different from buffered and unbuffered modules because of the notch position. For example, PC2-5300F memory is physically incompatible with PC2-5300(R/U), they use different slots. Not to get too detailed, buffered (or registered) memory, buffers part of the data whereas Fully Buffered memory adds an extra chip on each module called the AMB (Advanced Memory Buffer) and buffers all of the data. Because of the technology used in FB-DIMMs, they are both faster and even more reliable than registered (buffered) memory but completely incompatible.

Don't confuse any of these designations with ECC (Error Correction Code or Error Checking and Correction) which detects and corrects data errors during storage and transmission. This is a separate memory feature from above. For example, unbuffered memory can be ECC or not. I hope this helps.


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