@cadaveca
Well, good for you that all your PCs are that rock solid.
The old geriatrics I'm thinking of are things like P3s, P4s, Athlons (32 and 64-bit) some of which were work discarded prebuilt machines and potentially had some abuse, hence I wouldn't be surprised if they fell over when stressed too hard. In fact some are not even full PCs, being just a case, mobo and CPU in some cases, with the parts robbed to feed something else, lol.
+1 on perfectly "good" parts not working together. Sure, standards are created to ensure they do, but they sometimes won't as we know to our cost. Some reasons being things like standards that aren't quite robust enough, aging components which are drifting out of spec or components that just aren't made that well and therefore don't quite meet the spec in the first place or have loose tolerances within the spec. That's a great example with the mobo, since there are just
so many components on it which need to work to spec for it to go and of course the errors tend to accumulate rather than cancel out.
You'll like this story.
It's the summer of 2003 and instead of having a life like normal people, I build my first gaming PC based around a 32-bit 1.8GHz Athlon 2500+ CPU (ran reliably at 2.2GHz "3200+" speed with just a multiplier adjustment) an Asus A7N8X Deluxe mobo, an FX5200 AGP card (yes, yes, I know now, lol) and Windows XP Pro. I initially got 2 x DDR333 256MB modules for it. I did overclock them and I don't remember the exact speed reached, but it was slower than DDR400.
I then bought a DDR400 module of the same size some time later and sold one of the DDR333 modules (the poorer overclocker). Pair that remaining DDR333 module with the DDR400 one and I could overclock both sticks to something like DDR440, which was really impressive for the DDR333 module. However, run that DDR333 module on its own and it would fall over well before DDR400 speed. This even happened when I set the memory timings manually in the BIOS to match those set automatically by SPD when running the DDR400 stick. However, if I ran the DDR400 stick on its own, it unsurprisingly ran fine at its rated speed and I think hit DDR440 on its own, I don't quite remember now. The DDR333 stick I got rid of however, never did overclock reliably to DDR400 let alone to DDR440, regardless of the mobo slot I used. It might get to DDR400 speed, but then crash quite soon after. Note that the DDR333 sticks were matched pairs in terms of brand and model numbers, but bought as single packs, not in twin packs back then.
It looks like having a second stick in there running in dual channel mode somehow helped that superman of a DDR333 stick to run really fast and reliably overclocked and to this day I have no idea why this was the case. Any ideas?