Tough crowd......
Anyways some FAQ direct from the creators of memtest.....
1)Please be aware that not all errors reported by Memtest86 are due to bad memory. The test implicitly tests the CPU, L1 and L2 caches as well as the motherboard. It is impossible for the test to determine what causes the failure to occur. However, most failures will be due to a problem with memory module. When it is not, the only option is to replace parts until the failure is corrected.
2)There have been numerous reports of errors with only tests 5 and 8 on Athlon systems. Often the memory works in a different system or the vendor insists that it is good. In these cases the memory is not necessarily bad but is not able to operate reliably at Athlon speeds. Sometimes more conservative memory timings on the motherboard will correct these errors. In other cases the only option is to replace the memory with better quality, higher speed memory. Don't buy cheap memory and expect it to work with an Athlon! On occasion test 5/8 errors will occur even with name brand memory and a quality motherboard. These errors are legitimate and should be corrected.
3)Sometimes memory errors show up due to component incompatibility. A memory module may work fine in one system and not in another. This is not uncommon and is a source of confusion. In these situations the components are not necessarily bad but have marginal conditions that when combined with other components will cause errors.
http://www.memtest86.com/#philo
#2 is where I was at w/ my 512mb SDRAM pc266, Samsung chips....
Basically tried to "underclock" this stick below th 266 when it turned out that it would work at 200 but not 266. Didn't work. Not many choices in the ECS BIOS for this. Yes cheap RAM is cheap RAM but it can work. I've built 20 or so boxes, using various "budget" RAM and this is the first one to be unstable w/ generic RAM and NOT OC'd. Maybe I'm just lucky. Anyways works fine in a Celery box........
Opp's should add that I tried a 500Watt Ultra V (not the best but not the worst) PS before giving up on the RAM. PS made no difference whatsoever.