Someone didn't finish his homework. The legal, supported method of virtualizing OSX is:
Guest: Leopard Server
Host: ESX 5.1
Hardware: Mac Pro
Mac Pro is supported on the VMware HCL.
Leopard Server is legally virtualizable on Mac hardware.
VMware supports OSX Leopard as a guest on ESX 5.1
Mac Pro towers are going to be less dense, but given his cooling situation, lower density is probably a win. What datacenter wants 8 kW of laptop CPUs stuffed into a rack? Virtualization would also overcome the lack of redundant PSUs.
Guest: Leopard Server
Host: ESX 5.1
Hardware: Mac Pro
Mac Pro is supported on the VMware HCL. Leopard Server is legally virtualizable on Mac hardware. VMware supports OSX Leopard as a guest on ESX 5.1
Mac Pro towers are going to be less dense, but given his cooling situation, lower density is probably a win. What datacenter wants 8 kW of laptop CPUs stuffed into a rack? Virtualization would also overcome the lack of redundant PSUs.