It's been mentioned over at the DailyTech a short time ago that both Creative labs and Analog Devices have performed a series of tests on Realtek's current crop of audio solutions (most of which are found integrated in many motherboards on the market), this to confirm that they're incapable of being able to render EAX and EAX 2.0 effects properly even though Realtek clearly state that they can do it. Ouch!
Analog Devices and Creative Labs have made claims that Realtek's high definition audio solutions do not render EAX or EAX2 audio -- at least not very well. While Realtek's audio drivers have the proper driver flags to enable EAX and EAX2 in supported games, the listening experience presents a different story. Listening tests demonstrated by Analog Devices and Creative Labs show that Realtek's high definition audio solutions render EAX and EAX2 incorrectly, removing the 3D positional audio aspects and immersion of EAX and EAX2 completely.