ASUS P7P55 LE Motherboard

hey guys
im looking at the above mother board
i had a question regarding the 4x pcie slot, and was curious if anyone knew the answer

i currently have 2 pcie hd 4550's.

i dont do alot of gaming, but like having more than 2 monitors and do quite a bit of hd playback on my computer.

my question is if i get the above motherboard, would i be able to smoothly play 1080p back on the monitors connected to the pcie 4x slot.

i.e would the gpu in the 16x slot do the decoding for all my hd playback even if it was being played on the monitor connected to the 4x slot


thanks guys