With the prices of older ram spiraling out of control, im going the used route this xmas. I require either DDR 266 ( 2100 ) OR ddr 333 (2700) an acer t - 100. There is a person selling a stick of ddr 400 and told me most systems will downclock to the required speed? Is this true? i would love the idea of switching this to another computer if the person upgrades but will it conflict? isd the person making a story to sell ?

ddr400 ram is backwards compatible and will run at slower speeds if the mboard does not support ddr400. However, all your ram will run at the speed of the slowest module, and there are other factors that determine where the ram this guy is trying to sell you will work in your mboard. If you can easily try this guy's ram before you buy it, that's fine - it will either work or it won't, but if it wouldn't be easy to try it and return it if it didn't work... You must check out whether the ram you are thinking of buying is actually going to be compatible with your mboard before you buy the ram. Online vendors often don't have enough information about the ram for you to determine whether it will be compatible. There are many compatibility factors involved other than just the mhz it runs at and the PCxxxx rating. See response 5 in this for more info about compatibilty, and where you can find out what will work in your mboard for sure: http://www.computing.net/hardware/w... On many major web sites, you can also look up which brand name module ID number will work in which mboards.