Sound cards changing order on each boot

Problem

I have two sound cards in this machine:

 0000:00:06.0 Multimedia audio controller: nVidia Corporation nForce2 AC97 Audio Controler (MCP) (rev a1)
 0000:01:08.0 Multimedia audio controller: Ensoniq 5880 AudioPCI (rev 02)

The first is an on-board devices and uses the snd-intel8x0 module, the second is a Sound Blaster 4.1 PCI card, which uses the snd-emu10k1 module.