I installed two additional memory modules in an ASUS P4P800-E motherboard. The motherboard has 4 memory slots that take DDR1 memory modules. The system had two 1 GB memory modules already installed. I installed two additional 1 GB memory modules giving the system 4 GB of RAM, which is the maximum amount of memory the P4P800-E motherboard will support. I used Corsair VS1GB333 memory modules. After I installed the additional memory, I used the free MemScope Memory Tester software to test all of the memory in the system. I let the test run over night for six complete passes and part of a seventh pass with no errors found.
Note: you can download the MemScope Memory Tester software here. At the moment there is a missing image on the page that has a link associated with it for downloading the software. The link appears immediately below the "Test 7 Random Data Sequence Test" paragraph or you can click here to access the form you need to fill out to download the software.