CL speeds for memory modules
Thread Starter
Joined: Apr 2003
Posts: 28
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From: Berkshire
CL speeds for memory modules
Hey All
Upgrading the memory on my notebook and the current machine has an APACER PC2100 DDR Ram 128Mb with a CL figure of 2.
I've looked at Crucial.com and the like for a new 512Mb card but most if not all i see online have a CL figure of 2.5
Question is.. Will adding the 512Mb with the CL2.5 be a waste of time as the notebook will only use the memory with the lowest CL figure ie the 128Mb (CL2) card?
I understand the meaning of CL (CAS Latency). What i need to know is will mixing two cards of different (even if very minor) CL speeds work!
all replies greatly welcome!!!
Upgrading the memory on my notebook and the current machine has an APACER PC2100 DDR Ram 128Mb with a CL figure of 2.
I've looked at Crucial.com and the like for a new 512Mb card but most if not all i see online have a CL figure of 2.5
Question is.. Will adding the 512Mb with the CL2.5 be a waste of time as the notebook will only use the memory with the lowest CL figure ie the 128Mb (CL2) card?
I understand the meaning of CL (CAS Latency). What i need to know is will mixing two cards of different (even if very minor) CL speeds work!
all replies greatly welcome!!!
The Oracle
Joined: Aug 2001
Posts: 2,902
Likes: 0
From: Naples, Florida U.S.A.
kevindelaney,
Latency is measured in terms of clock cycles. For example, a CL=2 part requires two clock cycles to respond, while a CL=3 part requires three clock cycles. Thus, CL=2 parts complete the initial data access a faster (only 2/3 or the time) than CL=3 parts.
CAS Latency. This sets the CAS latency timing of the DRAM system memory access cycle when SDRAM system memory is installed.
If you would like to know a little more about the difference in performance you can read this review by Anandtech:
Mushkin & Adata: 2 for the Fast-Timings Lane
When you have two sticks RAM in your computer, the computer will default to the slowest stick's speed and timing unless you go in and set the speeds and timings manually. In your case the BIOS will default the speed of your RAM to CAS 2.5 PC-2100.
If you run WinXP you really need 512Mb of RAM. Running 128Mb just chokes it. You will see a much bigger boost in performance by having 512Mb of RAM than you lose going from CAS 2 to CAS 2.5.
Take Care,
Richard
Latency is measured in terms of clock cycles. For example, a CL=2 part requires two clock cycles to respond, while a CL=3 part requires three clock cycles. Thus, CL=2 parts complete the initial data access a faster (only 2/3 or the time) than CL=3 parts.
CAS Latency. This sets the CAS latency timing of the DRAM system memory access cycle when SDRAM system memory is installed.
If you would like to know a little more about the difference in performance you can read this review by Anandtech:
Mushkin & Adata: 2 for the Fast-Timings Lane
When you have two sticks RAM in your computer, the computer will default to the slowest stick's speed and timing unless you go in and set the speeds and timings manually. In your case the BIOS will default the speed of your RAM to CAS 2.5 PC-2100.
If you run WinXP you really need 512Mb of RAM. Running 128Mb just chokes it. You will see a much bigger boost in performance by having 512Mb of RAM than you lose going from CAS 2 to CAS 2.5.
Take Care,
Richard
