It certainly can create a great deal of confusion. It gets worse, because memory comes in different speeds, and some types don't work in some systems. Extended Data Out DRAM EDO speeds are measured in nanoseconds. DIMMs and SIMMs Way back in the dark ages of the PC architecture, I once owned an original Compaq portable. I upgraded my Compaq myself with an additional 384KB of memory by carefully inserting 27 individual 16KB RAM chips.
RAM now comes on tiny circuit boards.
If the 486 system will take SIMMs, you must only add them one at a time.