Hi,
Just played today with the board. I'm impressed.
In the first run, everything set to manual on lowest setting, it fired up my Q6600 at 9x400 Prime95 Small FFT and finally OCCT RAM stable (this one is very hard to get stable on high FSB and Fast memory with a quad core as it stresses the RAM-NB much).

I than, played with it about 2h and I'm running smooth 3.8GHz (8x475) so far Prime95 Small FFT and OCCT RAM stable, both for 2h each. This MB is impressing. When I read through the Maximus topic and all other X38 boards people fighting to get it stable at 9x400, I just

Above 3.8GHz, my Q6600 needs 0.05v increase for just 25MHz more speed, so worthless as the temperatures are already high for my setup

I'll target now full stability with 12h runs of Prime95 and OCCT in RAM mode. When done, I'll tighten the RAM timings and play with Static Read Control and Transaction Booster. Once done, I'll post my results with tons of photos.

By the way, the P5K Premium runs much cooler than my P5B Deluxe, but for this OC my board is already at 47°C with an OCZ RAM Cooler and an HR-05 IFX with a 80mm FAN at 5v on the NB, so it was usefull to change the stock cooling

I also run my Samsung HD, an SATAII 160Gb flawlessly. It looks like the problems are with new high capacity disks (above 250Gb)

And finally, many thanks for all of you, especially Sesdave for posting your setup and OC settings that helped me much to start with

Back soon with a full imaged review

Only regret: I lost so many months trying to get my P5B deluxe stable while I did 250Mhz better clocks on this one in a couple of hours, it rocks