RAM for ASUS P4P800 & P4VP-MX

Hello,
I have two computers and I'm going to upgrade their RAMs.

P4P800 has 512 Mb, DDR400 and I want to put in extra 512 Mb. This mobo has the Dual-Channel Mamory feature, Woudl it be OK just to add another 512 Mb DDR400 stick or their should be some other considerations?

P4VP-MX has 256 Mb, it has 533MHz FSB, but DDR400 memory stick (it said on the stick 400, DDR). I'm supposed to have 133MHz sticks with my FSB and my first question about this mobo is how bad that I have MSB 533MHz and that I use higher frequency memroy?

another one is, can I add another 512 Mb or it should be consistent and should be either two 256s or two 512s?

if I have DDR400 256, can I, say, add 256 Mb, but not DDR400, but someting like DDR333 or DDR266?

Thank you,
Yurich
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YurichAsked:
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simonlimbCommented:
>P4P800 has 512 Mb, DDR400 and I want to put in extra 512 Mb. This mobo has the Dual-Channel Mamory feature, Woudl it >be OK just to add another 512 Mb DDR400 stick or their should be some other considerations?

YES, but check to make sure the new RAM has the same CAS Latency (2.5, 3, etc...)

>P4VP-MX has 256 Mb, it has 533MHz FSB, but DDR400 memory stick (it said on the stick 400, DDR). I'm supposed to have >133MHz sticks with my FSB and my first question about this mobo is how bad that I have FSB 533MHz and that I use higher >frequency memroy?

With A 533MHz FSB mobo you should use DDR400 memory

>another one is, can I add another 512 Mb or it should be consistent and should be either two 256s or two 512s?

It is best practice to be consistent and use 2 x same Mb, but you can add memory stick of different sizes as long as they match in every other way, eg: CAS Latency, buffered/unbuffered, parity, etc...  Also, if you are going to add a stick of different size, put the higher Mb stick in the first memory slot.

>if I have DDR400 256, can I, say, add 256 Mb, but not DDR400, but someting like DDR333 or DDR266?

NEVER mix memory speeds, it won't work, eg: DDR400 + DDR333 will not work together.
Wildstar1869Commented:
With dual channel it is always best to just order another stick of exactly what you have in there to the model.  Sometimes differing companies will have differing regulations and the memory wont match exact.  If you buy another stick of the same model number from the same company all problems are ruled out.  This is what I did with my p4p800se MoBo and all was well, but it seemed slower when I added another manufacturers RAM that supposedly matched.
Gary CaseRetiredCommented:
Okay, let's consider this one motherboard at a time -- with a few intervening comments:

First, the P4P800:  "... This mobo has the Dual-Channel Memory feature ...

"... Would it be OK just to add another 512 Mb DDR400 stick..."  ==> Yes, with a caveat (read on)

"... or their should be some other considerations? "  ==> Yes, there are other considerations.  The primary consideration is that if you do not install the memory in matched pairs, it will operate in single channel mode.   Not the worst thing in the world, but it means your memory bandwidth will be reduced and performance somewhat degraded.   Note that the modules must matched (e.g. the SPD information is identical) or the memory will not operate in dual channel mode.

Is the current memory a single stick?  ... or matched sticks?    If it's a single stick, then adding another matching stick of memory will not only increase the amount of memory, but also provide better memory performance because it will then operate in dual channel mode.

---------------------------------------------
Second, the P4VP-MX:  

"... how bad that I have MSB 533MHz and that I use higher frequency memroy?" ==>  Not a problem.  Your system only supports up to DDR266 memory, so the higher speed module you have is simply operating at the DDR266 rate.

"... can I add another 512 Mb or it should be consistent and should be either two 256s or two 512s?" ==>  It makes no difference.  The board supports up to 2GB of memory, so you can use individual sticks of up to 1GB each.  It also is not a dual channel board, so that's not a consideration with this board.

"...if I have DDR400 256, can I, say, add 256 Mb, but not DDR400, but someting like DDR333 or DDR266?" ==> Sure you can.  simonlimb's comment ("NEVER mix memory speeds, it won't work") is WRONG.   There ARE systems which will not work with higher speed memory than specified (despite the claims of memory manufacturers for full downward compatibility), but yours is not one of them => as proven by the simple fact you're using DDR400 memory in a system spec'd for DDR200/266.   The downside of mixing memory speeds isn't that they won't work -- but that all modules will work at the speed of the slowest module, so you will reduce the memory subsystem's performance.   But your memory is already running at DDR266 speed -- so adding a DDR266 would have no impact except to increase the memory size.   If you added a slower module (e.g. DDR200) then BOTH modules would run at the slower speed.

One final caveat:  Memory modules are very sensitive to timing parameters -- and, particularly with the "no name" brands, modules that "should" work together simply don't.   There are also considerations of whether the memory is single rank or dual rank (single-side or dual-sided modules) that can impact how the memory is "seen" by the motherboard.   Glancing through the manuals for both of your systems I did not see any issues here -- but it's just something you should be aware of and always check in your manual before making assumptions about what will/won't work.   In your case, with these two motherboards, you should be fine.

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Gary CaseRetiredCommented:
Wildstar1869 - not related to this question, but with regard to your comment "... it seemed slower when I added another manufacturers RAM that supposedly matched..." ==> If it was in fact slower, then it's almost certain in that case that the SPD info was not identical, so the system operated in single channel mode.

Also "... If you buy another stick of the same model number from the same company all problems are ruled out." ==> It would be nice to think that; and with the major companies (Crucial, Kingston, etc.) it generally is true; but with many lower-tier suppliers this is not always true.   They often change suppliers, and even the same model number memory will not work in dual-channel mode if you happen to get two modules from different suppliers with any variance in their SPD's.    That's one reason most memory companies now offer "matched pairs" when you buy the memory -- this absolutely eliminates any possibility of this issue.
YurichAuthor Commented:
thanks a lot guys,

so, taking into consideration of what you said, I can buy two DDR400 512 Mb memory sticks (check if they support dual-channelling), put 'em in my p4p800, and the one DDR400 512 Mb from p4p800 add to my p4vb-mx, is it right?

a little bit consired with CAS Latency, since I'm not sure what it is for my current sticks and I'm not sure they put this info on them.

thanks again,
yurich
Gary CaseRetiredCommented:
"... so ... I can buy two DDR400 512 Mb memory sticks ... put 'em in my p4p800, and the one DDR400 512 Mb from p4p800 add to my p4vb-mx, is it right?" ==> Yes, that's a good plan.   Buying a matched pair will guaranteee no issues with dual channel support, and the 512mb stick should work fine in the p4vb-mx.  You can confirm that (just to be sure there are no spurious timing issues) by just moving the 512mb stick to your p4vb-mx now :-)

Don't worry about the latency -- it should be read by the system (it's reported by the memory's SPD) and set correctly.  If you do have any issues, you can adjust the setting in the BIOS -- but this is rarely required.


YurichAuthor Commented:
thanks, and moving my old 512 to my other computer, i can have 768, right? since I'm going to keep 256 as well.
Gary CaseRetiredCommented:
Yes - you'll have 768mb in the P4VP-MX and 1GB in the P4P800 after you do what you've suggested above.   ... and the P4P800 wll be running in dual channel mode.
YurichAuthor Commented:
excellent, thanks a lot
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