16 core Mac?

Howdy. I have been thinking about building a new computer and runing mac OSX 10.5. I saw a couple AMD quad socket motherboards available. That would give me a total of 16 cores. I was wondering if anyone has tried such a configuration. Is there a big difference between running AMD or Intel Chips?

I found this motherboard:

http://www.asus.com/products.aspx?l1...mp;modelmenu=1

And then drop about four of these puppies in there:

http://products.amd.com/en-us/Optero...il.aspx?id=412

I was wanting any of ya'lls input on this setup. I think I will probably liquid cool this system. Does anyone know about overclocking these chips. Thanks.