If you run a single threaded application set affinity to one core because windows will throw it about on many cores randomly and it can mess everything up. For instance, SPi will throw 25%/75% on Core 0 and 75%/25% on Core 4 alternatingly.

Lightman: I'm aware of 64-bit difference, we use them a work regular but the difference shouldn't be this much for me since I run a high NB/HT speed too. We've seen kyosens/stephens tests before this on K10h too on both for comparisons. My scores are looking lower than expected.