I wanted to chime in and cross link a few threads with some info I thought might help people. This thread seems "related" in a "set of four". I am going to post this same post on all four in an effort to help folks...
en.community.dell.com/.../19497619.aspx
en.community.dell.com/.../19456940.aspx
en.community.dell.com/.../20305446.aspx
en.community.dell.com/.../20298901.aspx
There are a ton of the C1100/CS-24's out there on eBay right now, and I am yet another on of the people who just couldn't say no and got one to user as a Hyper-V 2012 box (the no UI version). It just seems like about the best deal going to add some raw horsepower to your existing virtual environment (which I have at home because I am a geek and just enjoy this stuff...)
What thee threads seemed to my saying to me (IMHO) is that there seems to be some differences in the machines out there, and that all C1100/CS24's were not created equal. What I decided was going to be my personal indicator of "the good ones versus the risky ones" was would they take the most current (at the time of this post) C1100 bios from the Dell site (B23) and BMC firmware (1.82). I contacted a couple of the sellers on eBay to see if anyone knew about this, and (NO, I DON'T WORK FOR THESE GUYS!) I ended up talking with Peter Neiman from one of his eBay listings. Hopefully the moderator doesn't chip that link, because the guy earned the right to be specifically mentioned in my mind. He pulled one of the servers I was looking at and updated it to the most recent version to make sure it would work. Needless to say, not having to risk spending another couple hundred bucks to replace a board that fails to update as some people are seeing is worth a ton, so I bought mine from him. Again, I don't work for these guys, and I'm not saying you have to buy from them, but whoever you buy from, it might be worth asking about BIOS and F/W before you buy. That's my $0.02.
Hope I helped someone,
Jim