SLI Cards, have a question.

[TruthSeeker]

I just finished putting two SSD's in my computer and after I connected everything back up and reinstalled Windows 7 Pro, I noticed that on my BFG GTX-280 OC cards running in SLI, that only one fan seems to be pushing air out of the back of the card.

I was only surfing the web and not gaming, but is this normal?

Does one card basically shut off when not needed and running in SLI or do I need to order a new fan?