AMD cuts to the core with 'Bulldozer' Opterons

[SEA]

You miss one little point, hyperthreading can lower performance, this solution might even increase performance in single threaded applications.

That is a mistake.
Consider scenario:
1 thread is running on single core of BD delivering a 100% of performance.
2 threads are running on 2 cores within same DB module and delivers 180% of performance.
Now, 2 same threads are running on 2 cores of different DB modules. They deliver 200% of performance. So we saw a performance impact - 180% instead of 200%. And no performance increase...
And this is exactly as it would be with Intel's core with HT.