To reproduce/debug an issue exclusive to OS X 10.5, i was trying install Leopard on my Mac Mini (model "macmini3,1", came with Snow Leopard).  
However, when trying to boot from a Leopard install medium (tried both from DVD and USB stick) the machine just hangs:

 * with the selection screen still displayed when manually choosing the boot medium
 * with the bright grayish screen when running the install discs install option from Snow Leopard and letting it restart the machine

Does anyone happen to know what could cause this / how to work around it?  

Or could my models hardware be too new for 10.5? Although a web search suggests there were/are macmini3,1s with 10.5 running. Also, [this question and it's resource][1] suggest it should be working.


  [1]: http://apple.stackexchange.com/questions/4400/what-version-of-mac-mini-supports-leopard-10-5-8?rq=1