Prime 95 stresses the CPU not the RAM, it does stress some RAM to but it does not take it to 100% use age. If you want to check your RAMs stability run Memtest.
Your motherboard can handle 2GB sticks, come on its an X58, high end! Right click on my computer and select properties. It will tell you how much RAM the PC has.
Your fine, don't worry so much.
Hope that helps.