I've had this computer for a couple of years with no issues. Have a "unknown manufacturer" RS/RX480 MoBo, Athlon XP 3400 x2. Prior to last Friday, I THOUGHT I had (x2) 256 DDRRAM and (x2) 512 DDRRAM with one 512 and one 256 per channel, but somehow a 512 stick was missing and I had been running on 3 sticks for who knows how long. I finally broke down and bought some cheap PC2700 DDR SDRAM, x4 1gb sticks. Immediately after installing them, I began having "memory could not be read/write" errors from World of Warcraft. I ran Microshaft Windoze MemTest on the RAM and I got an error on the stick in slot #2. I removed the suspect RAM as well as from slot #4 which makes the board single channel and retried with MemTest. RAM in slot 3 failed with what appeared to be the same or relatively close results. I removed all but the first slot and ran again...Same results, "expected fffffff actual ffefff". I the put two ram sticks in slots 3&4 and 4 received the same erorr and yet the same again with only slot 3 occupied. I then put my original RAM back in, and you guessed it, RAM failure duplicates. I'm pretty sure MoBo is gone, but is there a test aside from what I have already done that will be conclusive before I just start "throwing parts" at the problem? Or would these results be a clear indication my MoBo has given up the ghost?
Use cpuid (also known as cpu-z, a free download) to check your board brand and chipset, as well as memory timings. You may have just bought some bad ram; could be high density or double sided. Single sided low density ram works the best.