When will DDR2 reach DDR1 CAS levels?

[therealnickdanger]

I'm coming off of a DDR-800 dual-channel CAS2 P4 desktop and going to a DDR2-667 dual-channel Core Duo notebook, but all DDR2-667 seems stuck at CAS5 while DDR2-533 is CAS4. While I'm sure manufacturers are trying their hardest to get DDR2 lower, what's the hold up? I'm set to buy some new RAM and I guess I don't want to pull the trigger until I know when to expect DDR2 CAS2 or lower... Help?

 

[Bobthelost]

It's not quite that simple really, the reason is that CAS 2 DDR 400 is the same as CAS 4 DDR2 800, it's the same time for the chips to respond, but the clock rate has doubled so in terms of latency it's doubled, but in terms of time between asking and recieving it's unchanged.

The latencies will decrease as semiconductor technology and processes improve, but it's going to be a slow improvement. Also since DDR2 uses a lower voltage that means you're going to have slower switching speeds.

 

[NuroMancer]

Originally posted by: Bobthelost
Not really, the reason is that CAS 2 DDR 400 is the same as CAS 4 DDR2 800, it's the same time for the chips to respond, but the clock rate has doubled. The latencies will decrease as semiconductor technology and processes improve, but it's going to be a slow improvement.

See bolded text.

 

[RyanVM]

According to a recent AT article, CAS3 is the lowest DDR2 will ever be able to get.

 

[fire400]

Originally posted by: RyanVM
According to a recent AT article, CAS3 is the lowest DDR2 will ever be able to get.

corsair XMS sticks have pretty low CAS on DDR2

 

[Bobthelost]

Originally posted by: NuroMancer

Originally posted by: Bobthelost
Not really, the reason is that CAS 2 DDR 400 is the same as CAS 4 DDR2 800, it's the same time for the chips to respond, but the clock rate has doubled. The latencies will decrease as semiconductor technology and processes improve, but it's going to be a slow improvement.

See bolded text.

Grrr, the rate that it improves at will be slow. :| 😀