What is difference between DDR2, 2RX8, 2RX16 and 1RX8 memories?

I assume DDR2 is the top of the pile.

Is it worth my while replacing the 2 G of 2RX8 with 2 GB of DDR2 i.e. am I going to notice much change in performance?

Never got a proper handle on RAM since it started going all DDR2/3 BUT IIRC DDR2 is not referring to the same thing as 2RX8.

Without knowing the details DDR, DDR2 and DDR3 refer to an evolutionary stage of RAM chips. I'm fairly sure the chips with 2RX8 designations are all DDR. DDR2 would therefore be better, the only problem being I dont think an older mobo can support it if it was designed for DDR. I remember this from when I was looking to upgrade mine and found I had to basically change everything.

Somebody may correct me but "DDR" is like a car model and "2RX8" is like the engine choice.

R is something to do with ranks, here

now I just need to figure out what it all means .....

ranks are the separate regions of a memory chip which can be used by the processor, the number after the X refers to the speed.

so if you want them ordering:

2 Ranks of X16
2 Ranks of X8
1 Rank of X8

it's to do with how many chips are on the modules and weather they are 2 sided.

if you have a DDR board you cannot put DDR2 or DDR in.

but if you have a DDR2 board you should put them in pairs as they have 2 channels from the bus into the memory to you get double the thoughput.

with DDR3 you have 3 channels so you have to put the memory in 3's.

laptop has 2 slots, one has 2Rx8 2 GB memory.

re: DDR2 - matched pairs - so not point me buying one of these since I would need to replace the one I have with DDR2, correct?

therefore I need to look at the R boards.

since my Vista is 32 bit, it cannot access more than 3 1/4 GB so fitting another 2 GB is wasting 3/4 GB hence 1 GB would make more sense, although 2 GB is not that much more £££.

So my options or a 1 GB carf are:
1 GB 2Rx16 or
1GB 2RX8

?????

No, you do not have to put DDR2 or DDR3 in matched pairs but it will help with the speed a bit.

If your board doesn't already have DDR2 then DDR2 won't fit unless the board has both DDR and DDR2 slots. They look almost identical but the notch is moved so you cannot physically put the wrong type in. You would be better off either way with 4gb than 3gb and if the cost is not much then I would go for the 4GB. Is it a name brand PC? If so what model and if not do you know what the motherboard model is, this is usally printed on the board near the graphics card slot.

If you know either then you can go to crucial.com and use their memory advisor tool and it will tell you exactly what memory it will accept.

[Edited on 29/4/2009 by Keith Weiland]

... now i am geeeting more confused...

so can DDR2 memory cme in 2Rx8 etc flavourrs?

what I have installed is

hynix (make)
2 GB (capacity)
so far so good...

2RX8 PC2 6400S 666 12

is that DDR2 or not?

(666 12 is speed related?)

read my update to my post above

yes PC2 is DDR2, ignore thr RX thing it has no bearing on this.

The 666 12 is the CAS ratings and has to do with the speed it can run at.

[Edited on 29/4/2009 by Keith Weiland]

quote:

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Originally posted by Keith Weiland

You would be better off either way with 4gb than 3gb and if the cost is not much then I would go for the 4GB.
About £ 5 difference

Is it a name brand PC?
Dell E6400 lappy

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Just to throw a spanner or two in the works, do you realise that laptop and desktop memory are different, you will need what are called SODIMMs. Also that laptop has a 64bit CPU so if you put XP 64, Vista 64 or Windows 7 64 bit versions on it you could use all that memory no problem. If you consider that then I would suggest waiting for Windows 7 as I have been using the beta for a while now and it is very good, way better than anything MS has ever brought out before.

Just go on the cruicial website and tell it what pc/laptop you have and it will list the recommended memory modules.

As Keith says you will need SODIMM memory for a laptop.

David

Could really throw an even bigger spanner in the works.
Depending on what you are using as an operating system could make you memory insignificant anyway.
Without going into too much detail, the OS 32bit XP and Vista will only take a max of 4gb roughly this inlcudes any graphics cards you use.
So, in laymans terms, if you have a 1gb graphics card you will only be using 3gb of you normal ram and any time.
Not exact but here are some links that explain what I mean:
http://www.tomshardware.co.uk/forum/page-251936_12_0.html
http://uk.answers.yahoo.com/question/index?qid=20080915080536AARp3xd
http://compreviews.about.com/od/memory/a/Vista4GB.htm