Xeons support both EEC and non-EEC ram. It' depends on the north bridge chipset on the motherboard if you must use EEC.

Some Opterons require EEC, some don't.

I became interested of finding the answer. It seems that answer is no.

http://serverfault.com/questions/433221/does-amazon-ec2-and-...

>AWS does not comment on this question. The general consensus (based on seeing this question asked on SO, HackerNews, Reddit and so on) is that, unless AWS specifically tells you the instance type is running ECC memory, you should assume it is not.

>Although unscientific and inconclusive I suppose this makes sense - ECC is a selling point, and the fact that AWS does not plaster "all our instances run ECC" on their info pages certainly suggests that they are not.