Factory-overclocked cards: whats the difference?

I was just wondering that apart from increased clock speeds what the difference is between, for example, a EVGA 8800GT and a 8800GT SSC or KO? Like, has the hardware changed subtly to accommodate for the increased frequencies (eg. increased fan speed) or are the ONLY differences the clock speeds?

to put it in a different way, if I were to overclock a EVGA stock card to the same frequencies as a SSC or a KO card, would they be identical in every shape or form?

eVGA explained it to me like this.

All 8800GTs come in from nVidia the same. After eVGA tests them all, they set the best ones (ones that have the potential to OC the best) aside. These become the SSC cards, they flash them with the SSC bios and package them as such.

Then the lesser high quality ones get KO etc. So the basic GT is identical, but all cards quality are different, just like CPUs, some OC better, some don't.

The ones that don't test well enough to be a base 8800GT get sent back or junked or whatever.

But they all come in as just 8800GTs.

And some are not tested and shipped with the EVGA sticker and are either DoA or crash after 5min inside a game... /sigh