Intel 855PM Chipset vs 333-DDR Memory support???

Posted on 2004-04-17
Last Modified: 2008-01-09
First of all, apology if this question is posted on the wrong 'topic' area.

I recently bought an ACER 804LCi with following specs: Centrino 1.7, 855PM Chipset.

The system comes with 512 MB (266-DDR) memory on a single bank. My questions are as follow:

1. Does the chipset support PC2700 (333 DDR) if I want to install one? (I have looked through the intel website, the 855PM product description webpage says it *does* support 333 DDR memory. But when I searched the net further, there was this white paper regarding the chipset, with no mention of 333 DDR, only supports for 266 and 200 DDR.)

2. If it turns out that I can install 333 DDR, can I mix and match? i.e. a 512(333 DDR) bank + 512(266 DDR) bank?

Hope someone can help me out, please. Thank you guys.


Question by:mowgli1977
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Expert Comment

ID: 10852100
Well thats a good question.......
As far as i know the DDR works like this
The empty slot shoud have the same equal size of memory i.e u have 266 the other slot should have the same size 266 if you can purcahase two 333 and replace it with 266 it will work...
But in case of SD RAM there can be mis match but DDR unfortunately it has to have a matching memory size.

Author Comment

ID: 10852425
Thanks for feedback surki1,

Just had a browse through the net again today, and it's turned out that the chipset supports not sure whether this is right?

...but still cant find the answere to if 855PM chipset actually supports 333...

Nevertheless, when I looked into a website of one of the acer notebooks online retailer, to check what kind of memory options are they selling for the acer notebooks, they didnt seem to make any distinction regarding which memory options (i.e. 333/266) will fit into which of the acer notebooks(which some are running on 855GM or 855PM or even AMD based system). I could only conlcude that if I buy the 333, it should work well with my notebook. But again, I dont want to splash out a lot of money only later to find out it doesnt work, and worst, most most retailers wont accept memory package which has been opened.

Any advice? Anyone?

LVL 69

Assisted Solution

Callandor earned 30 total points
ID: 10856031
With desktops, it doesn't matter that you put in memory that is faster than what is required by the cpu, because it will slow down to match the bus.  It's not the chipset that determines what speed the system runs at, but the cpu.  So though I haven't tried it, I am inclined to think that laptops behave the same way; if you put in faster memory, it shouldn't be a problem.
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Assisted Solution

ChrisSchumann earned 95 total points
ID: 10860281
Your laptop should work with PC2100 or PC2700 memory, but my hunch is that all memory will run at PC2100 speeds. I know the ThinkPad X31 uses the 855PM chipset and runs memory at PC2100 speeds, even though the newest machines ship with PC2700 memory. PC2700 is usually cheaper these days.

Author Comment

ID: 10860947
Thank you Callandor and Chris.

I am aware that faster memory, i.e. PC2700 will run at the fastest bus speed supported, i.e. 266, if fitted on such board.

I am trying to establish if it's any worth buying PC2700 (am planning to buy 2x512 MB PC2700) to replace my 2x256 PC2100. There is
1. Significant price different betwen PC2700 and PC2100 here in London, UK.
2. I thought it woud be nicer to get a faster DDR, and *actually* works at 333Mhz with my chipset.

But thank you for the feedbacks.

Accepted Solution

ChrisSchumann earned 95 total points
ID: 10861083
I looked at Acer's datasheet for this item (located here:$FILE/Datasheet_TM800.pdf) and it says the machine comes with DDR266 SDRAM.

That's another reason I think that PC2700 will not run at full speed.

Intel does say the 855PM WILL run at 333MHz, but the system designer gets to decide what speed to run it at. Everything that connects to the memory system has to run at that same speed. A lot of peripheral devices are still limited to 133MHz. They'd have to use 166MHz parts to allow the memory to run at 333MHz.

Last resort (from Acer UK site): Acer Technical Helpline:
If calling from UK : 0207 365 2486
If calling from Southern Ireland : 01 40732 14
For products out of warranty, please call: 0906 301 0001 between the hours of 09.00-17.30, Monday - Friday. Calls cost 50p per minute. Calls may be recorded for training purposes.
Acer e-mail support:

Author Comment

ID: 10871143
1. Rang acer, they didnt know anything, all they say. it's *possible, but we cant guarantee* so, that is as good as *dont know*

2. Am giving up

3. Thanks for feedbacks guys

Expert Comment

ID: 10871171
If you have a local vendor who will take returns, you can buy the faster and slower parts, and benchmark them in your system, and take back the slower or more expensive part.

If I were you, I'd buy the PC2100 if it's cheaper.

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