the Yorkfield Q9300 was a bit hard to overclock with the EX38-DS4 board at first, and i almost hate this board.
tried to add any of the voltages, either Vcore, MCH or FSB, or sometimes even PCIe and Vdimm to the overclock was a bit hard, because it won't get stable.
so i decided to check on the web just to see who else is having the same problem, then i found this pages
The Official Q9450/X3350 Overclocking Thread - Overclockers Forums yesterday.
there is a few guys at the forums who are using the EX38-DS4 also having some problem with a high FSB overclocking on Q9450,
it's at around 454-460 MHz under the EX38-DS4, and anything higher will require a fairly amount of chipset voltages increases,
but for FSB below 450 it won't require any of an additional chipset voltages, and the core voltage use in the overcloking is fairly low as well.
anyway, i now think, i end up liking this board after a few days of playing with it.
i hope it's not too soon to say this now, the EX38-DS4 might be the cheapest X38 board in the market, but it's a good motherboard indeed.
right now, i'm running Q9300 at 435x7.5 with a core voltage of 1.184V (in Windows), which's still below its stock VID, without any other voltages increases, and it's quite stable.
btw, ChaosMinionX, i think i also saw your posts on the forum as well.