Dual channel memory question

[arfondc]

Recently I added a 1GB stick of memory to my computer (before I had 2 512MB DIMM sticks). It now says as it's booting that it is in single-channel mode whereas it was in dual channel mode before I added the stick. Do I have to upgrade in pairs to keep dual channel or is it just a matter of just arranging the 3 sticks in the proper DIMM slots?

 

[Matthias99]

Welcome to AT!

PLEASE USE THE SEARCH FUNCTION. Questions about dual-channel memory are VERY COMMON and get asked all the time.

We also can't help you if you don't tell us important things like what kind of system this is. Intel-based systems can only run dual-channel with matched pairs of memory. Newer AMD-based systems hould be able to run in an 'unbalanced' dual-channel configuration.

 

[dguy6789]

Dual channel refers to logical channels that the system has located for the memory, to allow for a striping of memory. Keep in mind that a dual channel setup can have 2, 3, or 4 or more sticks of memory and run perfectly fine.

The most common and incorrect belief is the one that you cannot run dual channel with 3 sticks, or with unmatched memory. This is incorrect. Beyond two sticks, there is no magic number that you have to run the sticks in to get dual channel. The brand of memory does not matter either. 512MB of Muskin PC3200 and 512MB of Corsair PC3200 will both run together in dual channel without flaw as long as you run them both at timings they both can run at.

Understand this simple rule: As long as you have the same total amount of memory in each channel and all the sticks can run at the same speed with the same timings, then you can run dual channel without problem.

If Channel A has a 1GB stick and Channel B has a 1GB stick, it can run in dual channel. If Channel A has two 512MB sticks and Channel B has a 1GB stick, it can run in dual channel because there is a gigabyte of memory in each channel. If Channel A has two 512MB sticks and Channel B has four 256MB sticks, it will run in dual channel because there is still 1GB of memory in each channel.

As long as all the memory runs at the same speed with the same timings, the number of sticks does not matter, as long as there is an equal amount of memory in each channel.


Unfortunately, some motherboard makers are either cheap or lazy. Some motherboard makers only allow their board to support dual channel if you have only two sticks or only four sticks. There is no way to get around this other than getting a mainboard that has true dual channel support.

If your mainboard supports true dual channel, then you simply need to make sure you have the same amount of memory in each channel. If you put 1GB of memory in each channel and still have the single channel problem, then your board does not support true dual channel, only 2 or 4 stick mode.

 

[arfondc]

Ok I've updated my signature to include my system specs, thx