My laptop (Acer aspire 4738z) was running on 2GB DDR3 RAM on WIndows XP 32 bit. And I added one new module 4GB DDR3. Then it shows correctly the usable amount of RAM is 4GB.
Then I tried to install windows 7 while two modules are plugged but was not success(Cannot install windows 7 or ubuntu) .But I was able to install Windows 7 after removing newly installed RAM .
Now I cannot install new 4GB RAM because windows crashes while startup (Blue screen while loading windows logo).
Then I tried to install only new 4GB RAM bu removing the old one but the issue still the same. I installed a tool to check chipset it says it supports DDR3 1333 RAM (any way it worked with windows xp 32 bit). And also I have update the BIOS.