ECC, PARITY, and Nonparity
Most newer computers have SDRAM memory modules that support a chip set feature called EEC (error checking and correction). To see if your system board supports ECC memory, look for the ability to enable or disable the feature in CMOS setup or check the system board documentation. You can also look at your RAM. If a SIMM has an odd number of chips, most likely it is parity memory; an even number of chips usually indicates nonparity memory.. Parity memory validates the integrity of the data stored in RAM. If a parity error occurs, the CPU stops processing the data.
If you're getting "can't write to memory errors" you are probably using chip or damaged RAM. Memory chips and modules can be high-grade, low-grade, remanufactured, or used. Poor quality chips can cause frequent "can't write" errors or GPF's (general protection faults).
How to buy good memory:
-get the fastest speed your motherboard will support. Check the documentation. Look for something like "use 70 ns or faster." You can use 60 ns (you can go slower) but if you go faster, like by using 80ns, then you're asking for trouble (kind of like running downhill, you system will get going faster than your legs).
-don't mix speeds. Make sure all simms are the same speed.
-match your metals - if you have tin leads, get tin connectors ... gold, gold.
- stay away from remanufactured or used ... you can tell by looking at the CHIP ID stamped on the chip ... it identifies the date the chip was manufactured. It will most likely be in a YYWW format, where YY stands for year and WW stands for week. Example: 9910 ... indicates the 10th week of 1999. If the stamp is older than one year, don't buy it. If the stamps on the different chips on the memory stick show big differences in date (several weeks), it's remanufactured. LOOK FOR DATES RELATIVELY CLOSE TOGETHER AND LESS THAN A YEAR OLD.
-The surface of the chips should be polished, reflective. New chips look like this. If the surface is dull or matted, or you can scratch the markings off with a fingernail, suspect the chip has been returned, marked again, and then sold.
Lotta work ain't it?