NMI: Parity check/memory parity error

Try to clear the CMOS before you spend any money on new memory modules...

It could mean you have the wrong RAM type defined in the advanced chipset settings. If you are using NON-Parity ram in a machine set up for Parity Ram, you will most certainly get this error, because the memory controller cannot read the parity data back from the ram, if the ram doesnt report it in the first place. In this case, you should wipe the CMOS by following the Motherboard's instruction manual. If this is a corporate built machine (Dell, Compaq, et al) that might be more difficult, as I doubt they offer that information freely. In which case, look for a jumper very near the big battery on the motherboard, and remove/move the jumper's position and wait 20 seconds before moving it back. Alternatively, some machines can have thier CMOS settings erased by holding down the INSERT key durring power on.

(Parity is defined by 1 bit for every 8 data bits. If the value in the data bits is even, the parity bit = 0. If the value in the databits is odd, the value in the parity bit = 1. Non-Parity RAM doesnt have parity bits, and so cannot report this information. This is often the cause of this error. Parity is one of the oldest ram content checking methods in existance, and is less capable than more modern error detection mechanisms like ECC.)

If however, you have not tampered with the CMOS settings in any way, nor have you attempted to fiddle with the RAM modules, you may indeed be experiencing a genuine parity error--- This is often indicitive of a failing RAM module.

Some things to try before just going out and getting a brand new one though, include cleaning the edges of the RAM module with a white vinyl eraser. DO NOT USE PINK PENCIL ERASERS to clean card edges! Pink pencil, or pink rubber erasers contain acids and harsh abrasives that can harm the module and the slot that it gets installed in. Use white vinyl art erasers only!

The reason for attempting to clean the edges of the edges, is that often times the contacts of the slots themselves are NOT gold plated, and are often just aluminium pins. These can get oxidized, and then leave residue on the gold fingers of the RAM module. Cleaning of the pins in the slot is not advisable under any condition, however. The oxidation behavior of aluminium is that it produces a thin layer of oxide which easily comes off. Metal-metal contact between differing types of metal creates a haven for ion-exchange interaction, especially if electricity is present, which can induce this kind of oxidation (which is why you need to avoid getting acids on the RAM's gold fingers!) Cleaning the gold fingers on the RAM module is a quick and easy fix, and can solve basic communication problems to the RAM module. It should be attempted before replacing the module, to determine if there is an internal fault in the RAM or not.

If you RAM is dirty, you should consider taking the opportunity to clean the other card edges in your system with the eraser as well.

I have seen this oxidation problem occur in many areas with high humidity/ambient corrosive vapor present, and is actually pretty common.

In short--

1) Reset CMOS

If that fails

2) Clean RAM card edges with White Vinyl Eraser

If that fails

3) Replace RAM module