Most, perhaps all, Pentium motherboards require that SIMM sticks be installed in pairs. The next thing to check is the access time. A motherboard that supports 70ns RAM will also work with 60ns RAM, but if your motherboard manual specifies 60ns or faster, it will burn out a 70ns stick. That is, you add up the 1s and 0s, and if the result is even, the parity bit is 0, and if the sum is odd, the parity bit is 1. The parity bit value is saved when data is stored in the memory, and checked when the data is read, to ensure that the data read is not corrupt.
RAM chips have become much more reliable, so parity checking is generally unnecessary now.
But if memory errors can be expensive for you, consider RAM with parity. That's a pretty good indicator that parity is no longer needed. The type of metal used in the pins and the slot is often ignored. Some use gold, some use tin. Do not mix the two.