X58, to be honest I don't think there are any waterblocks for it yet. Mainly because the memory controller, which was a large part of the NB that needed cooling, is now integrated in the hot as hell CPU.
I've seen a diagram explaining the i7 architecture and noticed the NB as part of the CPU, but there is another bit below the CPU that the QPI feeds into. Don't have the link at work and can't remember what it was called. I'll look it up later.