If it really is DDR RAM, it must be among the first made. PC1600 means it's DDR-200 speed, and so not worth anything for recent systems.
As for being electrically compatible, the ECC normally isn't an issue, as most MBs will ignore the extra ECC bits and use the main part of the RAM as non-ECC RAM. However, ECC RAM is almost always "registered" or "fully-buffered" RAM, not "unbuffered" RAM. That's because almost the only computers that use ECC RAM are servers, and servers typically use registered or FB RAM and can't usee unbuffered RAM. Conversely, typical desktop MBs can only use unbuffered RAM.
Bottom line: your module might be suited for a late-90s server MB.