Now as some of you have read, I've purchased an HP Microserver Gen8 with a Celeron G1610T inside which does support ECC. I purchased a second-hand Intel Core i3-2120 but as soon as it arrived my colleague said "well that's lame, it doesn't support ECC". I researched the internet and came to a sad conclusion. There seemed to be no official support for ECC. Why risk ruining a "production" server with a non-ECC capable CPU? So the CPU disappeared in my desk.
A few months laterI re-did some of my research and realised that HP did offer the Microserver with i3 processors from the Sandy Bridge generation. This meant that the hardware should be capable and knowing that most of the cpu's from a certain family probably are from the same wafers it wouldn't be too far fetched to assume that most (if not: all) of the chips from the same series should be able to support ECC.
Long story short
I'm running the i3-2120 now in the Microserver Gen8 and it works perfectly. ECC is shown as enabled in both the iLO and unRaid. No issues whatsoever. An i3 CPU of this generation can be found second hand between 25 and 45 euro's (approx.). And don't worry about the TDP except if you're hammering the system 24/7. My temperatures haven't gone up at all :). So I can recommend this upgrade to anyone wanting to get some more oomph from their Microserver Gen8 with a G1610T in it (which is a great deal on it's own!).