I'm talking from personal experience. I've built PCs for friends and never had RAM issues. I just used the techspot list of mobo recommendations for first gen with a combination of 3000 and 3200MHz RAM (there was a period when 3200MHz RAM was very expensive). For me, 3000MHz has always worked regardless of the die type.Thats not true actually, on most mobos and cpus you cant run 3200 with anything but bdies. I had 3 r5 1600 with 3 different mobos, all had the same issue
I would be happy about the upgradability if the price of a mobo wasn't inclided in the price of the cpu. With the 3d being 450 euros, you ARE paying for a motherboard, you just dont get one, you have to stick with your old outdated one.
And again that's not the point. You are talking about a slight RAM speed reduction for a 5yo PC. Do you understand just how big of a difference the CPU will make from such an upgrade if you have a compatible mobo? (I don't expect OEMs to release bios updates to all first gen mobos)