When attempting to install RAM into a system it refuses to boot with an error claiming "SDRAM width of 4 is unsupported, must be 8 or 16". Various sticks of RAM work just fine on the machine, and the RAM that it won't accept works just fine on other machines. All of the sticks are DDR3-1333/PC3-10600 and the sticks that don't work vary between 4/8GB sticks (though other 4/8GB sticks work just fine).

I cannot see any real difference between the modules that work and don't work on the machine, so my question is: "What does SDRAM width refer to, and how can one tell the width of a stick based on the label?"


It means the chips on these DIMMS are probably high-density modules. There is some information on the Wikipedia DDR SDRAM article.

There is also some more information about at http://1ststop.net/


What you are looking for is likely going to be labelled as DDR3-1600 • 1.5V • 128Meg x 64 •

for instance, this is a 1 GB stick of ram, made up of 64 chips of 128Meg each (128Meg x 64 in the description above)

This information was taken from crucial.com. I wasn't able to find any with the high density option as indicated above, but that may just mean they don't sell them.

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