The issue may be related to the voltage setting of your memory modules. The standard operating voltages of DDR2 and DDR3 memory modules, as defined by JEDEC, are 1.8V and 1.5V, respectively. However, some of the memory modules require higher operating voltage than JEDEC’s standards. In such case, the memory may sometimes not be able to function properly without enough voltage.
When you encounter instability issue, please first check the operating voltage of your memory modules, and please manually set the memory voltage accordingly in the BIOS.