Some mobo's don't like the SPD timings that come preprogramed on Ram, I know mine didn't. It would be helpful if you could add your spec's to your sig so we can help you better. Do you know what you Ram timings are? Also your mobo manual should have a beep code book that will tell you what the beeps mean.
Most of the time its just that most Ram these days use anywhere from 1.8-2.4 volts, thats what I'm guessing it is.
Yes. If you can boot up and run on 1GB in single channel mode you can try 2GB dual channel (in most motherboards thats one stick in each of the same colored slots.
If 1GB boots but 2GB dual channel does not - try 2GB in single channel mode. 1 stick side by side in the different colored slots.