This could be explained:
Possibly Electronic Noise, since the CPU is working so much that the bus becomes very noisy(Electronically) which could spread through the board to your Sound Chip through the Power bus. This can't be fixed unless you want to do really hard mods on your motherboard(Soldering, Wires, etc.)
seriously, you're just making stuff up. crosstalk would occur regardless of how "swamped" the bus is- which means not a single computer made would work.
Crosstalk is a problem, but only to the engineers.. or I suppose if you make some offbeat modification.
Anyway, I guess I'll add something relevant-
you can sort the processes by CPU usage by clicking the CPU time column in the processes list- alternatively, you can try
Process explorer