Will my motherboard handle one matched pair of dual-channel memory and one non-matched stick?
Posted on 2006-04-28
I have a Dell PowerEdge 400SC. It has four memory slots that accept sticks of up to 1GB DDR 333 or DDR 400. I have confirmed the configuration of the slots. There are two that are black and two that are white. For Dual-channel to work properly I have to match the RAM sticks in conjunction with the colors. Not a big deal. Here is the issue though, and will make this a two part question, so more points...
I had 2 matching 128mb sticks in it before along with one 512mb stick. I purchased two matching 256mb modules (512mb total) thinking that the server had two matching 256mb sticks and one 128mb stick because it read 768mb. So:
My thoughts: Actual:
2 x 256mb DDR333 2 x 128mb DDR333
1 x 128mb DDR333 1 x 512mb DDR333
Then remember I bought two more 256 mb DDR400 sticks. So my total modules is five. My intention is was to upgrade to 1GB Dual-channel memory working in Dual-channel mode. However, we can see by my diagram that I cannot do that now. What I have done is put the two new 256mb DDR400 sticks in the correct dual channel slots. If alone, they would be working in dual channel mode, I have confirmed this. I have also put the existing 512mb stick in one of the unmatched dual-channel slots. See below:
Slot 1 (white): 512mb DDR333 ---------|
Slot 2 (black): 256mb DDR400 ---| |
Slot 3 (white): <Empty> -----|-----|
Slot 4 (black): 256mb DDR400----|
My first question is: Will this degrade or negate the performance of the correctly matched 256mb DDR400 sticks? The Server booted and shows 1GB for memory. But I'm concerned that I have lost the Dual-channel capability.
Second Question is: If the 512GB does negate the dual-channel of the 2 x 256mb sticks then which would be more efficient or faster: a) using the two original 128mb sticks in the white slots and the two new 256mb sticks in the black slots (768mb in dual-channel mode)? or b) sticking with the configuration i currently have running in what I would assume to be single channel mode if you have gotten this far in this question (1GB in single-channel mode)?
I know it's a lot, but I hope my description has made it clear what I'm doing and what I'm looking to recieve for an answer. Any questions, let me know. Thank you