I have a Dell 4600 (800FSB) with two 256MB Samsung DDR400 PC3200(3.0-3-3-8) 2.5V sticks. I like to add two 512MB sticks. Crucial site recommends CT306585 (DDR PC3200 • CL=3 • UNBUFFERED • NON-ECC • DDR400 • 2.6V • 64Meg x 64). I have found cheaper Crucial memory (CT6464Z40B) at other online shops. This model has identical specs as CT306585 but Dell recommends it for ASUS, ABIT etc. My questions are: 1. Will CT6464Z40B work on my Dell 4600? 2. Will the new 521MB sticks work without problems with the existing smaller Samsung RAM stcks? Thanks in advance.

If the Crucial part # is different then the specs can't be identical. Crucial guarantees the recommended memory will work. I think that is the way to go. From my limited experience with Dell, they are fussy about memory. What does your manual say about the RAM modules?

The Dell manual says to use 184-pin DDR400 PC3200 non-ECC unbuffered memory sticks. I thought Crucial may be giving different part #s as a marketing strategy. The specs posted on the Crucial web site for CT6464Z40B and CT306585 are the same.