Hi Mcguyver, Welcome!
What kind of pc and a bit more info on your system!
The most common cause of parity errors when first booting up the PC are incorrect configuration or using the wrong type of memory. It is unusual for an actual memory failure, of the type that parity checks for (meaning, you wrote one value into memory and read back another value with a bit changed) to be encountered at the start of booting, although it is possible.
This usually means several things:
1) Memory is not seated properly- make sure memory is plugged
in well and clips are in place.
2) If you have 2 slots try to see which slot is 1 and 2. Put in one
chip at a time.This way you can see if chips are bad.
3) Make sure you have the right memory for your system.
Im by far no expert on memory and parity has me a little confused. But I have put as good an explaination as I can get:
An error detection technique that tests the integrity of digital data within the computer system or over a network. Parity checking uses an extra ninth bit that holds a 0 or 1 depending on the data content of the byte. Each time a byte is transferred or transmitted, the parity bit is tested.
Even parity systems make the parity bit 1 when there is an even number of 1 bits in the byte. Odd parity systems make it 1 when there is an odd number of 1 bits.
There are 12% more memory cells in 9-bit parity memory than there are in 8-bit non-parity memory. To shave costs, many desktop computers are built with non-parity memory; however, sometimes you can choose to use either type.