Sound through 2 DVI/HDMI ports simultaneously

I have set up a computer to run power points on 2 - 50' TV's in our company breakroom. For some reason the audio in (3.5 mm) on the TVs will not work. I am runnin a GT 640 card using DVI to HDMI cables to feed the video. I can run the audio through 1 or the other one of these cables, but not at the same time. (WIN 7) Is there any software that will allow me to send audio through both these cables at the same time?

Look in your sound settings there should be a box to check

No there is no setting..Win 7 only supports 1 sound output at a time...thats why I was asking about software