In case people don't know
Credit to some random guy not on this forum:
"From the Product code, new stepping has SLACR at the end,
old stepping has SL9UM
Only real difference is a 10w reduction in power consumption, most are hoping this will equate to "better overclocking", but it's still "the luck of the draw", some of the newer E6600 cpu's don't all overclock as well as the earlier ones, or need a little more vcore to reach the same speeds,
running at stock though, the new Q6600 stepping should run a little cooler."
Either way, I say best option now is to go to a store and demand to see the processor box since the product code seems to only be written on the top