Problem with RAM

BIOS is already updated.

When you tried only two dimms, were they running in dual channel or single channel mode? The motherboard selects this automatically depending on which slots you use. I'm wondering if perhaps your motherboard is able to run them fine in single channel mode but is unable to run dual channel, which requires a higher level of compatibility. Have you tried three sticks?

Hi,

In the manual of my motherboard it said:

Do not create a three-DIMM configuration in dual-channel mode. The
third DIMM is ignored in the dual-channel operation.

yeah the idea was to force the motherboard to run in single-channel mode, because most memory incompatibility problems imo stem from dual channel. When you are in single-channel mode a memory request means the bits stream along without interruption from one single dimm to the cpu, doing so one dimm at a time. But in dual channel mode those bits are streaming from two dimms simultaneously and are quickly "joined" once they get to the memory controller, which makes dual channel mode way more complex than single channel mode and way more dependent on perfect timing, which is why it can result in incompatibility problems with certain dimms

Back in the day when everything was single channel you could buy the cheapest memory and it always worked. But as soon as dual channel came out, memory compatibility became a problem and you have to be picky about exactly what memory you get for your motherboard. In my earlier post I was hoping that your motherboard would drop into single channel mode if you installed a third dimm, but from what you posted it looks like the third dimm is just ignored. But my principle is the same - the only way you are going to get your machine to address 4.00GB with your CURRENT dimms is to get the memory to run in single channel mode.

At some point you have to ask yourself if all this is worth it, because a machine with 2.75GB is pretty unlikely to perform any differently than a machine with 4.00GB.

I understand everything what you said but there is some difference between using 2 something GB of ram or 4 something GB of ram. Now when my computer is using 2...GB I have the most 600Mg memory free. Before when whole ram was used I had 2.6GB free memory it means everything was working always faster and smoother.

P.S.
Another thing I don't understand this thing which I see in the System Total 4.00 GB (2.62 GB usable)
What it means usable?
It doesn't have any sens !!!

zungul said:

Another thing I don't understand this thing which I see in the System Total 4.00 GB (2.62 GB usable)
What it means usable?

It means your motherboard knows there is 4GB installed in the slots however it also knows it cannot run it all properly in dual channel mode because your dimms are not up to snuff. Like if you buy a dozen apples and 4 of them are bruised, you would have 12 total apples in the kitchen but only 8 usable apples.

This first time when was 9Mb it was 2and 4, but later I tried 1 & 3 and was the same sytuation but a little more than 9Mb about 28Mb. I think still good.