Dustie wrote:
> hi all
>
> my PC is 4 years old and getting a bit sluggish. It only has 512mb of
> memory so I want to get another 512 and slot it it. However, I'm baffled as
> there seems to be about a billion different types of memory to get. My
> motherboard is an Intel 845PE. Can some kind-hearted soul help the thickie
> here and tell me what I need to get? I followed the advice of a friend and
> got a "PC133 168-PIN SDRAM" chip off Ebay but found it was completely wrong
> (which is why I'm asking here now! 
>
> cheers
>
> daz
>
>
The 845PE takes DDR memory, and a maximum of two double sided sticks.
For example, PDF page 111 of this doc (Section 5.2) talks about it.
When I can get them, a chipset document helps double check the
memory options (in cases where there is an argument).
ftp://download.intel.com/design/chipsets/datashts/25192401.pdf
You can also go to
www.crucial.com or
www.kingston.com and use their
search engine, to find some RAM.
You can use PC2700 or PC2100, and matching what you've currently
got makes the most sense. Even a stick of PC3200 could be used,
but is not really going to help you (the extra speed cannot be used).
Sometimes I recommend buying PC3200, as it may be easier to sell
later, but maybe it is better to just match what you've currently
got and save a few dollars.
In the Crucial listing for this example board, they have a PC2700
CAS Latency (CL) = 2.5, 184 pin DDR DIMM for $47.99. Use your
particular motherboard model number, to get a similar list. The
lower the CAS number, the better the RAM, but the lowest CAS
that can be used, is going to be limited by one of your two
DIMMs.
http://www.crucial.com/store/listparts.aspx?model=D845PEBT2
The motherboard will pick a slow enough setting, so that both
of your DDR DIMMs are kept within spec. Say, for example, you
currently owned a PC2100 and your new one is PC2700. The BIOS
will operate both DIMMs so that the PC2100 is not run past
its spec. That would be DDR266 transfer rate, or a 133MHz memory
clock, so both DIMMs run like they're PC2100. If both DIMMs
were PC2700, the BIOS could use DDR333 transfer rate, or a
166Mhz memory clock signal. So the BIOS auto setting should do
most of the thinking for you.
As I understand it, the front side bus speed of your processor,
also makes a difference as to what frequency options are
available for the memory. So if you had an older FSB400 processor,
then perhaps only the DDR266 option would be available. There
is no reason to panic, as faster memory can run at lower speeds
(less stressful) without a problem. Again, the BIOS will do
the right thing.
You can use a tool like CPUZ, and list the characteristics of your
current RAM. That will help guide you as to what to expect, based
on the combination of the two DIMMs.
http://www.cpuid.com/cpuz.php
Use the SPD tab in CPUZ, to see what is stored in your current
DIMM's internal timing tables. Of course, looking at the
sticky label on the DIMM, is another way to verify its
nominal speed.
At this late stage in the game, another thing to be aware of,
is you are investing in an older memory technology. You may
not get to recoup much of your $47.99 if you decide to upgrade
the whole system tomorrow.
Paul
>> Stay informed about: what memory chip do I need for my PC? 
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