[ale] RAM upgrade question

Calvin Harrigan charriglists at bellsouth.net
Mon Jun 26 11:43:15 EDT 2006


Courtney Thomas wrote:
> Maybe what I should have said is........
> 
> Since the Cache Latency is not manually set in the BIOS but is reported 
> as Level 2 Cache 512 KB,..... should I assume it's automatically 
> detected and so I can use CL3 as well as CL2 ?
> 
> OR, does it mean I can ONLY use CL2 ?
> 
> Gratefully,
> 
> Courtney
> 
> 
> 
> JK wrote:
>> James P. Kinney III wrote:
>>
>>
>>> On Sun, 2006-06-25 at 16:39 -0500, Courtney Thomas wrote:
>>>
>>>
>>>
>>>> I need to increase the RAM capacity from 128 to 512MB in a portable.
>>>>
>>>> I've located some SODIMMs, whatever that means,
>>>>
>> Small Outline Dual Inline Memory Module, IIRC. "SO"
>> refers to the form factor.
>>
>>
>>>> that appear to match the 
>>>> docs on my machine's RAM requirement, except that said modules are CL3, 
>>>> not CL2.
>>>>
>>>> Of what significance is this ?
>>>>   
>>>>
>>> If you are replacing CL2 with CL3, it should work OK as long as the rest
>>> of the parameters match up. Don't mix the two types or else the RAM will
>>> not work. The CLx is a timing designator. I can't recall whether it is
>>> refresh rate or write rate. The main thing is that all the RAM must be
>>> the same type.
>>>
>> And you may need to adjust your BIOS for the lower CL (cache
>> latency) setting. Some BIOSes require CL to be set manually.
>> Some allow different CL settings per bank, IIRC.
>>
>> -- JK
>>
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I'm pretty certain CL refers to the CAS Latency.  CAS = Column Address 
Select(Strobe).  It's the latency from when a new column of memory cells 
are addressed and valid data is appears on the data lines.   It has 
nothing to do with cache.  It's basically how fast the memory is.  The 
lower the number, better the memory performs.  Replacing 128M of cl2 
with 512 cl3 will actually make memory access slightly slower overall, 
but that amount of memory will need less swapping.  No matter how slow 
the new memory it is still several orders of magnitude faster than swap 
space.  So the overall system will definately be more responsive.

Calvin...



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