I'm really starting to wonder where people are getting SP1. I heard if you were an MSDN member that you could get it, but it hasn't been rolled out to my computer yet.

The performance effect of AVX is really quite amazing, but as Anand's SNB Architecture Review says, AVX is able to take advantage of the SIMD INT units for FP ops. This effectively doubles the performance you would've seen with SSE only, as linpack is an FP-heavy load and does not use much integer math. This lines up with a lot of the LinX screenshots we've seen from other members at the same frequency with no SP1.