Or, it's just plastics out-gassing. Put the cables in a well ventilated area for a couple days and see if the smell goes away. Costs you nothing other than some time.
That's what I was thinking too, so I opened the window and sat them in the sun for part of today. I'll keep them out for awhile.
In any case, my impatience got the better of me, and I ended up ordering a set of those replacement cables (which were more expensive, everything included, than the PSU itself) - yeah, this, even before I checked to see if the PSU was indeed as quiet as it's advertised to be. I guess I could cancel it once I try out the PSU, which I'll do tonight, smelly cables or no.
The replacement cables are nice as they come in many colors; I like the idea of power cables being a different color than all the others (I ordered green). Silly me.