Good question. I'd expect the -60 would have been cheaper than the -66 so some bottom feeder might have bought them up, but this is Asus, so about as premium as motherboards could get in those days.

It's even weirder looking at date codes - I can't make out any on the chipset, but can see one on the RTC: 9607. The keyboard controller is even newer: 9617. Same for the UMC I/O chip. That makes this board a very late i430FX board, a few months past the launch of the i430VX and HX chipsets. Yet it's built like a very early FX board, with asynch cache and a COAST slot - and that -60 chipset. Odd.