I recently bought 4GB RAM as my system had 3 GB RAM only, So i replaced 1 GB with 4 GB. But the problem is that the new 4GB ram is 1.35 volts and the older 2GB RAM is 1.5 Volts. System is working alright, but i am worried. How will i know if its ok for my system. I have done system tests and no issue arise.