General discussion

PC3200 vs. PC3200U

What is the difference between pc3200 and pc3200u (u=unbuffered?) Shouldn't this be important enough to mention on web sites like (I may know viruses, but memory escapes me -

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Where are you seeing PC3200u ??

Suspect buffered -unbuffered is addressed on mem mfg websites...sure its not there ?


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Here you go
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Registered (+1 tiny black chip) versus Unbuffered RAM memory

Thank you ! Strange how I would notice - over many years - the 8 larger black chips - but never notice that one, much smaller, tiny black chip. So "registered" chips are the ones with the "U". These chips have a clock cycle delay. The Unbuffered chips are the one without the "U" (sounds like reverse polish notation). It also means I can not "mix and match". But in this case: I can remove the 256mb unbuffered chip, and replace it with two 256mb registered chips. Thus putting 512mb safely on the computer - a step up. Of course, this all assumes the chips "fit" (one versus two notches - and not on a Dell which moved the notches thus making their memory "propriatary").

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You might have better luck if you told us about the system

instead of about the RAM that doesn't work. To be honest I doubt the RAM is proprietary unless the original MB is a server board....cause all the PC66, PC100, PC133 that I've seen is on the same PCB design ...168 Pin SDRAM with 2 notches...some single sided, some double sided.


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IBM Compatible versus Dell Propriatary

The primary question was general in nature: A customer had given me a few choice sticks of RAM instead of CACH (cache? bad pun?)So, when I went to CHEQUE (check) the ram, found it had that U (pc3200u) whereas other sticks were w/o the u (pc3200). As for the more specific nature of propriatary RAM - check out a DELL motherboard: The notches on most(?) sticks of RAM are off by a fraction - thus forcing you to buy ram directly from Dell instead of your friendly neighbourhood computer warehouse.

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Custom made RAM? Extremely unlikely. Entirely too expensive.

"IBM compatible" could mean compatibility with any number of computers produced over the past quarter century. Too vague.

If the notches are misaligned, even by a little, you're probably using the wrong type of RAM.

The best way to learn what type of RAM works or is compatible with a computer is to go to the computer model's webpage and look at its specifications. BTW, WHAT DELL MODEL IS IT?

An alternative is to enter the computer model number at a site like or They will display information on what of RAM they sell is guaranteed to be compatible.

You could also download and run CPU-Z ( to learn all sorts of information about the RAM modules currently installed in the computer. It is yet another way of learning what TYPE of RAM is compatible with your computer's motherboard. It will even give you the manufacturer name and model number of the RAM module.

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The 'u'

The 'u' that you see may be part of a model number scheme for a specific manufacturer and not necessarily part of an industry standard designation.

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Hmmm....well don't forget there is PC3200 DDR 400

184 pin, buffered and unbuffered and the DIMM notch is slightly off-center. If we knew what PC mfg and model number we could probably back into the RAM type.

Your call.


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The "U" means "Unified", buffed.

The"U' you see is buffed and is mostly proprietary!

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