I suggest you install the latest drivers on the Asus download page for you model. The 400 series drivers had problems, I think from 6.0.1.10600 and up have most of the Bass Speaker fixed. Check out this thread on adjusting your equalizer or this one workaround the subwoofer. If these threads don't solve your problem you may have a hardware problem. The VIA Driver 600 and above do not call it Sub Woofer. Its now called only a Bass Speaker. Your particular problem I have not seen before but still I would try the later updated drivers I personal haven't seen much difference in the drivers since the 600 they all solve most of the problem with the Bass speaker. None of them actually make it a LFE speaker. I myself just loaded the 6.0.10.1400 and to me it hasn't changed much since the 600 drivers. It's listed in the VIA HD Deck as a Bass Speaker, you still have to adjust it manually, It will not adjust with the volume controls in sync with the left and right speakers!