RAM - get memory with the highest bandwidth and lowest CAS/tRCD/tRPD/tRAS

Me and my collegues where a fortunate few who managed have our machine upgraded to have 1Gigabyte of RAM. However, during the upgrade process our vendor faced a lot of dificulties as most of the machines refuse to boot and some were throwing memory errors when booted or running. The reason he gave was that our original memory installed were from Taiwan and the new ones were from China. When I came across this article about RAM specifications, I think it is because the memory that he tried to install was incompatible with the current RAM or mainboard. There seem to be a lot of other specifications other than the bus speed or the size of the memory that we need to determine to be compatible and suited to our systems before we plug it in. Most of our vendor, technicians and system administrators will never had hear of the terms CAS/tRCD/tRPD/tRAS.