Most computer users always have issues with Ram upgrade.this can help you

PROBLEMĀ I bought two matching RAM modules for my father’s Dell Dimension 4600 PC after checking they were the correct type and size. But after installing them in the ‘Dimm 1’ and ‘Dimm 2’ slots, the computer displays the dreaded blue screen of death. When I reinstall the old RAM, all is well again. What have I done wrong? Phil Moore
HELPROOM ANSWER You’ve bought the correct RAM for your Dimension 4600. The RAM in this system works in dual-channel mode, meaning you can fit a matching pair of RAM modules in either ‘Dimm 1’ and ‘Dimm 2’ or ‘Dimm 3’ and ‘Dimm 4’ if you’re adding more of the same type of RAM modules.
However, it’s possible that you have purchased a faulty stick of RAM. An easy way to check is to install one 1GB module in the Dimm 1 slot and power up your PC. If it works, this stick is fine. Do the same for the other Dimm you bought.
If both modules work fine on their own, you may need to download and install the latest Bios from the Dell support site. The last update was released in September 2004, however, so it’s likely that this has already been installed. Having done this, try installing both modules again.
If the problem persists, revert to the PC’s original RAM configuration and download one of the many memory-checking utilities available at Snapfiles. Use it to check the individual modules for faults.
If a fault is discovered, contact the supplier for a replacement.
Remember to earth yourself against a radiator or other metal object before handling and installing any component in your computer.

culled from http://www.pc advisor. com