On Oct 14, 5:08 am, wrote:
I bought some used DDR2 DIMMs to match a pair what I had already. I inserted them into my good PC and it would not boot - no display, not even a beep error code.
So I removed the suspect DIMMs, and still my PC does nothing. Only after replacing the original DIMMs with a third pair did the PC boot.
Next I put the suspect DIMMs in a spare computer, and it gave beep code for
memory failure (has a different mainboard to the other PC). Also tried the original DIMMs that were good, and found they also give bad beeps. So it appears that I got some bad memory which furthermore damaged the original RAM in the nearby slots. I contacted the seller who swears on a Judeo-Christian storybook that they were A-OK when he posted them. They were wrapped in an anti-static bag.
I have been building and upgrading PCs for over 15 years, and have never zapped any modules. And both PCs were set at standard frequency and voltages.

What can cause memory to fail other than incorrect voltage, and what
other than the MB's initial draw on the PS to provide that final stage
of regulated memory voltages? All else being normal spec'd. When my
MB was giving me problems, the voltages registered not so far out of
the norm, but what was happening, I think, is the crappy MB capacitors
were straining like all hell. It was to the point of prematurely
wearing out PS units. So, even though everything is reading OK to a
novice looking at programs/sensors reporting voltage setpoints, it's
not really. Things are fluctuating way out of wack at some level
beyond those readings, and, meanwhile, I'm replacing power supplies
every year or two under ****-poor assumptions. When you test a car
battery for instance it's put under a load for a truer sense of how
voltage interacts with current. Not what it displays on a $5
multimeter. Same with those sensors to my way of thinking. How do I
know...I really don't. I just watch for the little abnormalities and
don't dismiss them if they're going to carry over or turn into a
bigger issue. I try and get the stuff right, good components, but
there's always something to watch because I'm a sucker for old-assed
gear when it looks good and priced right. Another thing. No computer
I've owned is ever the same. They've all got their personalities and
sometimes age into something else.