I've been using the same motherboard for over a month, works great. There's a whole discussion here about how ithe DP43BF won't support 2GB modules without a BIOS upgrade. And flashing a new BIOS can be tricky, you can't jump from an earlier version to the latest, you have to flash it with incremental builds until you get to the latest.
As for your problem, try installing just ONE piece of the original memory stick and see if it completes post and you can get into the BIOS. Corsair writes on their website that some motherboards have great difficulty running 4 slots of memory even if the motherboard has 4 slots. They also write that unless you buy a matched kit of 4 memory sticks, installing a second matched pair with an earlier matched pair may or may not work.
I'm currenting using a pair of Corsair CM3X2048-1333C9DHX