Can I safely have 2 x 1 GB sticks and 2 x 2 GB sticks? All specs are the same, but they are single and dual rank respcectively. The system (and BIOS) sees them. I am wondering because I have a chronic problem with the OS not being able to install USB devices -- mass storage. I have done exhaustive software checks and even changed out the motherboard and installed both Win Vista (32 bit) and Win 7 Pro (64 bit) with no luck yet.
I removed the 1x 1GB and moved the 2GB DIMMs to the vacated slots. The problem persisted. I recently changed OSes from 32-bit Vista to 64-bit Win7. I have not updated chipset since doing so since Dell support site does not identify any changes. Note the OS change was an effort to resolve my USB problems after exhaustive software fixes tried.