Installing RAM over the MOBO limit?

Hi there, I've been away from this community for a while but it's good to be back.

I'm currently bringing my old desktop pc (Dell XPS from 2006) back to life to use it as a test machine.

It originally shipped with a whooping 1Gb of RAM on 2 x 512 mb sticks. Later I took those 512 mb sticks out and installed 2 x 1gb DDR2-800 sticks (A total of 2 gb of RAM). This was the current configuration until this morning. Dell's manual says the MOBO has 4 slots (True :) ) and each one supports either 512 mb or 1 gb sticks for a minimum of 512 mb of RAM and a maximum of 4 gb. It also says it supports DDR2-553, DDR2-667 or DDR2-800 ram.

So I had this 2 gb DDR2-800 sitck lying around and decided to add that stick to the system and see what happened. To my surprise BIOS as well as Windows recognized the stick with no problem and indicates that the system now has a total of 4 gb of RAM (I'm running Windows 7 64 bit now). Also I want to mention that I've never updated the BIOS.

Perhaps the manual says it supports a maximum of 4 gb by the limitation of Windows XP back in the day but the manual is pretty clear stating that the slots have such limitation and not because of the OS. I will try to get another identical 2 gb DDR2-800 sitck and see if the available RAM in Windows increases beyond that 4 gb limit stated in the manual. Since they already lied in the amount of RAM per slot allowed, I think it's worth trying.

So the system right now is like this:
DIMM 1: Mushkin 1 gb
DIMM 2: Mushkin 1 gb
DIMM 3: Adata 2 gb
DIMM 4: Empty

Best case scenario for me is if the system ends up allowing 2 gb per slot so I'm able to install a total of 8gb.

Here comes the question:

If the system recognizes only 4 gb of Ram, what is best, Having all slots working on 4 x 1 gb or 2 x 2 gb with two slots empty?
The MOBO does support dual channel memory.

Thanks for your help

personnaly i would go with the 2 x 2GB
to verify can go to crucial and do their memory scanner it should tell you the max the computer can have. memory | United States (USD)

There are anomalies with computers, I have a Dell Dimension 4600 that has Vista on it. The BIOS accepts up to 4GB RAM, 1GB in each of 4 slots. Vista is 32-bit and most times a 32-bit OS will report somewhere between 3.2GB and 3.5GB RAM in Properties of Computer/My Computer. For whatever reason this one shows all 4GB RAM [DDR PC-3200], appears to be working fine. I changed from 2.5GB just for kicks and the computer is actually working a bit faster, may be the previous mix of single-sided and double-sided modules versus the current all single-sided modules. They are actually matched modules, same brand, same numbers, etc.

All this to say it's best that each pair be matched to each other and if possible pairs matched to each other. Then there's the colored slots, actually the clips, that denote matched slots.

And I do agree with going with Crucial, have never had a problem.

This is a picture from the Dell manual:


And here is a picture from the Crucial website:


I went to the Dell support site and entered the service tag on the PC's case to get info on the system and it told me that my system was in fact a Dimension 9200. Not surprising at all giving the similarities between the XPS and Dimension systems at that time.

Anyhow, Crucial also says my Mobo has a 4 gb limit. I'll try to get that second Adata 2 gb stick and report the results here just in case it helps anybody with an old system like mine.

Thanks for your help!

Your welcome that us know how it went