ECC memory uses additional parity bits to verify that the data read from memory is the same as the data that was written. Without this check, memory is vulnerable to occasional corruption where a bit is flipped spontaneously, for example, by background radiation.
ECC memory solves these problems and has been available for over 50 years yet most personal computers do not use it.
What gets Torvalds’ goat is that is that Intel has made ECC support a feature of its Xeon range, aimed at servers and high-end workstations, and does not support it in other ranges such as the Core series.
During a discussion about AMD's new Zen 3 Ryzen 9 5000 series processors on the Real World Tech forum site one person said that he didn’t see AMD's unofficial ECC support being a big deal.
However Torvalds snorted: "ECC absolutely matters. Intel has been detrimental to the whole industry and to users because of their bad and misguided ECC policies. Seriously. And if you don't believe me, then just look at multiple generations of rowhammer, where each time Intel and memory manufacturers bleated about how it's going to be fixed next time... And yes, that was -- again -- entirely about the misguided and arse-backwards policy of 'consumers don't need ECC', which made the market for ECC memory go away."
He added that the arguments against ECC were always complete and utter garbage. Now even the memory manufacturers are starting to do ECC internally because they finally owned up to the fact that they absolutely have to.
Torvalds said that Xeon prices deterred usage. "I used to look at the Xeon CPUs, and I could never really make the math work. The Intel math was basically that you get twice the CPU for five times the price. So for my personal workstations, I ended up using Intel consumer CPUs."