Ash HN: Does Apple buy the Cheapest ECC RAM, sell it for 4x markups?
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I wouldn't expect for Apple to sell any memory without a huge markup, so let's not focus on the 4x for this paragraph: In general "cheapest != worst". The combination of memory and other hardware has to be stable (that's were part of the markup comes from - Apple guarantees your system to be stable [I'd expect]). So if CL22 memory is still fast enough for the general work load they'd expect, then it's also good enough.
Edit: And, as others pointed out over on Twitter: It's possible that they have multiple sources for memory, and you just get what they currently have in stock. Plus, even if their RAM always ships with the same memory chips, it's not sure the stock photo shows those they actually use.
Personal opinion: The x4 is why I don't buy Apple and recommend them to anyone who needs a lot of power. The bang-per-buck ratio is just terrible (even if x4 seems extreme even for Apple).