Hi,
I'm looking for a site that is at an intermediate level. I know what a motherboard is and does, I know what pci, usb, . . . are. I have assembled my own pc more than one time, and I know what to buy.
I want a site that takes me through the more technical aspects of what chipsets are made of, what the north and south bridges are (I can't find any site that has this!), . . ..
Anyone know a good site?

One site that comes to mind about indepth stuff is Ars Technica. They may not have everything you're looking for, but they do go fairly well into depth, so prepare for some heavy reading. The have a well done article on RAID levels for one.