UDIMM vs SODIMM?

What does UDIMM memory mean? How does it compare to SODIMM?

 

Is that U actually a Mu and therefore a UDIMM actually a MicroDIMM? A MicroDIMM is basically laptop memory with a smaller form factor than the standard SODIMM. As far as I know, they're not compatible at all, and laptops using MicroDIMMS are few and far between.

 

Wolf, thanks for responding. I just found this:

"what is UDIMM - shorthand for Unbuffered DIMM (a DIMM without a register or buffer)"

But what does that mean? I assume it's a minus to be "without a register or buffer"? Does it affect anything significantly?

Edit: here are more details, but I just want an answer to my simple question above

 

http://en.wikipedia.org/wiki/Unbuffered_memory

Buffered memory is indeed usually only used in servers and commercial applications. My laptop uses unbuffered memory, your laptop probably uses unbuffered memory; the standard memory you buy at Fry's or Newegg is unbuffered memory. The added reliability of buffered memory is really a case of adding more nines onto 99.99%.

 

Not forgetting that you also lose performance for the sake of reliability.

 

MicroDIMM was only used by SONY in a few laptops

All laptop memory is unbuffered, there is not one laptop made which supports Buffered memory
There are buffered sodimm's out there, just beware of them, they are usually used on raid cards, server workstation cards, old matrox cards, and some server motherboards

If you have a laptop, you want to buy standard sodimm memory

Error checking memory is as fast if not faster than unbuffered memory. I have PC6400ECC memory in my workstation, it generates more bandwidth than the PC6400 corsair in my brothers desktop


K-TRON

 

So both SODIMM and UDIMM are unbuffered, according your explanations, then what's the difference? I was looking at lenovo outlet and saw most x61s had UDIMM, while x61 had SODIMM.

 

They're the same thing. SODIMMs are unbuffered DIMMs.

 

What is the link you found the terms? Is it "uDIMM" or "UDIMM". The first is microDIMM, which is a different form factor. The "u" is actually the greek letter "mu" which means micro. Some small form factor notebooks use this type of memory.

 

Micro dimms are about 1/2" shorter in length than a standard sodimm memory card.

When UDIMM = unbuffered memory, than it is the same thing as sodimm memory

There are three categories of sodimm memory, DDR, DDR2 and DDR3
You need to know which your system uses, so that you buy the proper memory. Each DDR type has a different slot, so you cant put DDR3 memory into a DDR2 slot, and so forth

K-TRON

 

If your laptop is really old, the sodimm inside the laptop might be the 4th category, the 144pin SDRAM sodimm

 

yes that is true,
if you go back even further, you get bubble cell memory, and non standard memory, which connects to the motherboard via a slot

Pre DDR based systems can be very picky with the memory you put in them, so with older systems, I am talking pentium 3 and older, its best to use certified memory for your system

K-TRON