i have a emachines t5048,and i had another emachines t2643,and i took the 256mb memory out and tried to put it in the t5048,but it wouldnt go in any1 no why?
I couldn't find any specs on T2643 so I'm not sure. Do you know what kind of RAM it is (PC2100, PC2700,etc?) Even so, putting anything other than PC3200 in your T5048 would be pointless. Your bus speed is 533MHz, if you put anything other than PC3200, 1) you may get some serious lag issues by mixing PC3200 with something else and 2) you're wasting the potential of the machine. I'd recommend getting some dual-channel memory to put into the T5048.
i could not find anything on the T2643 either, i did find the T2642 and it took a totally different RAM speed. The 5048 took 400MHz PC3200 and the 2642 took 333MHz PC2700 most likely they are just not the same. Use this to see what you need, but you have to research as some T5048 machines take DDR and some take DDR2 http://www.crucial.com/#