Can I mix Cas Latency ratings?



New Member

It's my first time to upgrade memory. My system is a Compaq Presario 4400US and has 128 MB of memory. My board has two slots and support up to 512MB of memory. One slot has the 128 MB, and the other i'm planning to use with a 256 MB module. I went to and tested the tool and it say that my system needs this memory.

Module Details:

* Crucial Part Number: CT284665
* Module Size: 256MB
* Package: 168-pin DIMM
* Feature: SDRAM, PC133
* Configuration: 32Meg x 64
* DIMM Type:
* Error Checking: Non-parity
* Speed: 133
* SDRAM Timings: CL=2
* Specs: SDRAM, PC133 • CL=2 • Unbuffered • Non-parity • 133MHz • 3.3V • 32Meg x 64

It cost $70. It is bit expensive. Well, I bought one for less money on the internet, It is almost the same, but with different CL rating. Here are the details.

, CL3

I think micron work together with Crucial, so its good.

But, As you can see it has different CL rating. Do you think it will work in my system? I want to be sure.

I've read about CL rattings, crucial say CL2, but i bought one that has CL3. I don't know about tweaking the BIOS just in case, I checked in my presario that i need to press f10 instead of f1 (to go to the BIOS), but still i can't find how to see/edit "CAS latency ratings" or "memory options" in the BIOS. I think Compaq Bios doesn't have it. I just want to know just in case there are compatibility problems. I'm bit worry about this..I hope you can help me. Thanks in advance.


New Member
just try installing the new ram and see if you have any problem. if you have problems, try switching the locations of the ram modules. you can also run ram test utility after installing the ram to see if it detects any issues.

i have mix different cas rating modules in laptops before without any problems.


New Member
You should be okay. What will likely happen is that the system will run all the memory at CAS3.