cas 2, cas 3, whats the difference

[Guest]

well.. im a newbie.. what exactly is the difference betweem cas 2/cas 3 memory?

is my 256 mb Apacer mem cas 2 or cas 3?

thanks
ebola

 

[FatBurger]

Don't know, you'll have to check with whoever you bought it from. Or set it to CAS 2 and see if it'll run.

CAS is the latency of the RAM, or how fast it responds to requests. You can set it to 3, which will make it slightly slower, or 2 which will make it respond slower. Not all RAM can run at CAS 2, but most can.



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[Guest]

ok.. thanks.. ill check with the store and apacer themselves..

whats best? cas 2 or 3...

and i have seen people mention this in relation to OC'ing.. how will this interefere with OC'ing.. im guessing a high FSB will kill it if its low quality memory..

 

[FatBurger]

CAS 2 is better.

When you overclock your FSB, then sometimes the RAM can't handle the extra MHz at CAS 2, and you have to bump it to CAS 3 to handle the extra speed. Lower CAS is better than higher MHz, until you get above 150 or so.

Basically, stick with CAS 2.



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[whoha]

So, without overclocking, are you saying that 100 SDRAM @ CAS 2 is better than 133 @ CAS 3? And keeping more in the oranges vs oranges vein, how much difference would there be between CAS2 and CAS3, both @ 133? Any benchmarks or helpful reviews to point to?

I've been puzzling over this for some time, and am especially confused after reading Crucial's FAQ which implies that CAS2 isn't that much better than CAS3 since the clock cycle saved by CAS2 is only saved once at the beginning of the burst of data.

One of the things I'm interested in is video. Should this be an area where CAS2 really makes a difference?

Also, if you don't mind shifting to a thought about DDR RAM, Crucial has only CAS2.5 so far in the 133 equivalent (PC2100?).

If I buy an ECS SIS735 (K75sa or so), would I be better off paying extra for Corsair CAS2 RAM (vs Crucial's 2.5), or does it really matter? Thanks for your thoughts.


Cheers!

 

[upec]

The difference is very small. I did not notice any difference in performance after I change my RAM from CAS 3 to CAS 2.

 

[FatBurger]

I disagree. 100MHz CAS 2 is faster than 133MHz CAS3. I saw a change of about 150 in my memory benchmarks when I went from CAS 3 to CAS 2. And my benchmarks more than doubled when I did all my optimisations.



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