Help me with this DDR2 decision

[AMD K9]

I bought a Dell Dimension 4700 with 256mb DDR2 (400mhz) and they are a pair for that setup, which I assume is 2-128mb modules. There are 4 slots available, and maxes out at 4gb. Can I just add single chips or will that throw everything out of balance? Crucial recommends MATCHING PAIRS on their memory advisor, but the person I talked to says there would be no ill-effects if I just added say a 512mb chip.

I didn't want to go with Dell for their 512mb config, as that would have been 2-256mb modules, leaving only 2 slots left, plus it was a more costly upgrade than buying it elsewhere.

In a years time after memory prices fall, I would probably have 1 - 1gb chip, 1 - 512mb chip and the original 2 banks (256mb total) for a grand total of 1.768 gb. Would this work or will there be flaws and negative consequences?

 

[AMD K9]

impatient bump

 

[smithdj]

With Dells, you need to install matching pairs or ram (dual-channel). The HUGE thing with Dell is matching CAS Latency. Not familiar with DDR2 but, with dell ddr, they come factory at Cas3, if you but anything other than CAS3, the dell would drop the mhz. (example : Originally pc3200 @ 400mhz, would drop to 333mhz if you put anything other than CAS 3.) I hope this helps

 

[AMD K9]

What is CAS3? Could I just take out the Dell memory and use aftermarket stuff to avoid the CAS3 thing? How come Crucial memory told me I could use a single stick of memory without any problems? Is this a DDR2 requirement, that wasn't a problem with DDR?