That's awesome. I think my wife would punch me if I got into the habit of dumpster diving, but there have been multiple times where I've seen what looks like awesome equipment (monitors, computers, surge protectors, etc.) being thrown away near universities and office buildings, and I always have to resist my hoarding nature to take them.

Four cores and 12gb of RAM would make a pretty solid build server, with enough room left for a Minecraft and video streaming server to boot! Sounds like a pretty awesome find.