One BD module has also 2MB of L2 while 1 SB core has only 256KB. So without L2 ,one bulldozer core(if possible to be viewed like that) would be around 7-8mm^2 and with 1MB of L2 it would be around 14mm^2. But aside of that,2 IB cores will probably just be slightly smaller than 1 BD module.How much performance you expect from 2 IB cores?It is basically SB shrank with probably same amount of L2 per core.Clock will be boosted probably,but at the expense of TDP. By that time AMD will have Terramar ,20/10 core server and 10 core desktop chip based on improved Orochi design. 25% more cores and 25% more TDP headroom for Turbo boost clock on improved GF 32nm SOI hk/mg process. That one module is just 30mm^2 more Vs Zambezi/Valencia and it brings 25% more performance. That's the beauty of Bulldozer design .