Hi MSIMAX!
I tried pulling the HTT to 400 (in bios) and there was no problem on booting (As before the processor is still at stock speed), and the overclocking capability wasn't changed.
The same happens also on 255HTT
But I noticed that The system shows signs of instability when reaching 750MHz of DDR2 speed even if we set 533 or 667, so the main problem is related to the barcelona IMC which isn't capable of handling memory speed over 667 (maybe 750MHz is the tech limit).
If we place a couple of DDR2400 memory that is capable of reaching 750 MHz, we could overclock our barcelonas up to 3.2/3.4 GHz...
However neither bank interleave or node interleave options are disabling the dual channel mode.... WTF!!!!