I found the issue! (actually, I found it awhile back, but forgot to post it here.) The problem seems to be a IRQ/data conflict between the audio on-board and sata drivers in nvidia's proprietary driver for the motherboard. (which is why it didn't show up when using old nv driver) The problem was fixed by changing position_fix in driver options of sound card to 1. Now official nvidia driver works fine, sound doesn't glitch, and computer doesn't crash. Glad it was a simple fix, though finding it wasn't. Hope anyone else with this issue finds this solution.