Both, the Intel® Thermal Solution STS100C and Intel® Thermal Solution STS100A, are for Intel® Xeon® processors in server/workstation systems featuring 2 LGA1366 sockets. Thus, any of these could work with the Intel® Xeon® Processor E5520, fine. You need to check on the type of chassis as while the STS100C is a passive/active combination heat sink, with removable fan, the STS100A is active heat sink, with fixed fan; see the following URL:
As for "weight, fan dimension, fan speed and noise level", etc., I'd recommend contacting any of the Thermal Solutions Suppliers found here:
Suppliers don't provide technical data about products beyond what the vendors document. This isn't their job. When I asked for detailed information, they replied: "Ask Intel"
So I ended up buying a STS100C, and wrote a full review on it, so that the technical data is finally available to the public. This review is available on my home site at:
Hopefully the information provided there will be useful to others.