I built several systems with the DS3, and no cold boot issues (or any other issues). The P5B Dlx is nice, but pricey. Though, with your choice in ram, it seems you like to spend money. So, the P5B Dlx suites your build. No board is worth > $150 IMO. My most expensive board was the DS3, and it was only $120 when I bought it; and I consider that EXPENSIVE. They lowered the CPU prices but jacked up the Mobo prices, lol.
I think the 9500 is easier to install than the Freezer 7 Pro (which uses the stock intel mounting method). The Freezer 7 Pro is great for its price (~$20)... though, you're spending trends should lead you to the Tuniq Tower or Zalman 9700. Otherwise, save money on the ram by dropping to some non-dominator CL4 sticks, and use the saved money on a Tuniq. Dominators are a waste of money, IMO. There are plenty of other choices out there fore less money, and perform just as good and sometimes even better.