[ale] RAM upgrade question

[Jay Finch]

Hi Courtney!

I've been using RAM of different CAS (CL) levels in various machines (both
servers and workstations) for years, and it's worked fine for me.  As
Calvin stated, when you install RAM with a higher CAS Latency, it does
"slow down" the CL2 RAM to run at CL3 (unless you override it with
overclocking features), but the difference is negligible.  (I've kept my
eye on CAS for years when building my Gaming/Performance machines, and for
THOSE applications the CL (CAS Latency) can make a difference.

No worries about mixing and matching - Just make sure that your memory
types are the same (DDR, DDR2, ECC, etc) and your memory SPEED is the same
(233, 300, 400, 533, etc), and the rest is just details.

Hope that helps!

Cheers!
Jay


> Thanks Calvin.
>
> I think it'll work fine as I was just on www.memorysuppliers.com and
> they have memory for my specific machine that they guarantee to work and
> it's "CL3"   :-)
>
> Cordially,
> Courtney
>
>
>
> Calvin Harrigan wrote:
>> 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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>>>
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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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