What's the most recent Mac that will run Leopard? We have edit bays (13) and use Mac Pro 2.1's and Mac Pro 4.1's both dual Xenon  quad core.

When a computer dies, we usually look for the same motherboard which are getting harder to find over time. Hackintosh and Quo are out - they seem too sketchy. We are looking for options to run Leopard to maintain compatibility with the SAN.

What is the most modern/recent motherboard or Mac that will run Leopard?
These sites can be useful for such questions:

http://www.everymac.com/systems/by_capability/minimum-macos-supported.html

http://www.everymac.com/systems/by_capability/maximum-macos-supported.html