I've noticed that the rear ports have some problems as well. I think it's due to the fact, and don't quote me here, that the rear ports have less power going to them. I think I remember reading this somewhere. For instance, one of my larger USB joysticks takes a lot of juice. For some reason, it wouldn't run right on the rear port, but when I hooked it up to the front port, it ran fine. Meanwhile, I have a smaller USB Gamepad that ran perfectly on the rear ports. I think it just has to do with the power output of the ports.
The EAX issue though, I believe it is the drivers themselves. Some people have been having issues with it and one way to resolve it is to run an Mp3 in Windows Media Player then pause the song. Minimize Windows Media Player and start the game. It fixes the laggy sound. I believe Hercules knows about the issue, it has to deal with Directx8, but I'm not sure when they are going to release new drivers to fix it. I hope this helps and good luck. I use a Herc GTXP myself and I think it's a great card, drivers are still a bit immature but if Hercules gets off their ass, it will be an incredible sound card.