Well there's a bunch of problems. Could be high energy particles flipping bits, but that's very rare. Could be a row hammer attack flipping bits. Could be a

Well there's a bunch of problems. Could be high energy particles flipping bits, but that's very rare. Could be a row hammer attack flipping bits. Could be a flaw in the memory chip, dimm, dimm socket, motherboard traces, CPU socket, or inside the CPU. Without ECC any of the above will crash an app, or even the entire machine. With ECC you'll get a log message, and if it's a single bit error it will be automatically repaired. If it's not fixable and it's in userspace that application is killed (and the kernel logs the error), if it's in kernel space the kernel will panic. So generally it makes your machine more reliable, and easier to debug. Generally repeated errors are a fault of some kind and you can easily tell which dimm it is. Without ECC you end up troubleshooting all causes of crashes, and even if you know it's memory, you can't be sure which dimm it is. So I think it's well worth the minimal premium to make your machine more reliable, and if it's unreliable it's much easier to track and fix the problem. Amusingly without ECC heavy CPU use with parallel gcc compiles causes a particular error. Not sure if it's in the FAQ, but it's well know that the particular error means you have a CPU/RAM problem, common with memory errors, CPUs that are too hot, or overclocked CPUs.