Sorry for the confusion... I never actually needed to do this before. But, it looks like you would need a converter like this one:
http://www.ebay.com/itm/4K-x-2K-HDMI-to-HDMI-and-Optical-TOSLINK-SPDIF-3-5mm-Audio-Extractor-Converter-/151879472737
Basically, HDMI out form your video card, into the converter... then OUT from the converter you'll have HDMI to your monitor (using an HDMI to DP cable), and Audio out to your speakers...
Again, I've never used those so I do not know if it would cause any video lag or not... for gaming, that would be highly annoying. But it might be worth a try.