Usually its a simple case of looking at the label on the stick. So for 1GB sticks- You need to find the chip config which is 64Mx8 or 128Mx4 HIGH Density = 128Mx4 LOW Density = 64Mx8 For 512MB sticks- You need to find the chip config which is 32Mx8 or 64Mx8 HIGH Density = 64Mx8 or sometimes 32Mx16 LOW Density = 32Mx8 or sometimes 16Mx16 Obviously you would want to AVOID "High Density" as they are only compatible with 10% of motherboards. "Low Density" has 100% compatibility with motherboards. With high density they put more memory on each chip, so some motherboards dont recognise all of the memory, maybe half. low density as you can see put less memory onto each chip, but is infact the same amount of memory as the high density sticks, so low density is the choice to go with.
It very difficult without a label of some sort or writing. Another thing is they are usually unbranded without a manufacturers make. But this isn't always the case. When buying the memory its best to purchase from a respected retailer, rather than private sellers like on ebay which has the majority selling of high density ram. But if you know what your looking for and the seller has stated the density, fair enough.
depending on how much ram you are dealing with whether it is single sided or double sided. double sided is usually low density & single sided is usually high density depending on the ram amount involved.
