I have a 2011 MacMini with an i7 2.7GHz and a discrete GPU AMD Radeon HD 6630M with Thunderbolt. No IGPU.
Actually, you do. Its hardwired into the chip itself - every i series chip with the exception of the i7 extremes come with Intel HD Graphics, I believe its HD3000 in the mini's CPU. But in the case of the mini, the discrete GPU means the IGPU isn't used.