Most GPU cooling systems make almost the same noise. You won't notice a difference in Db if it's smaller than 5 Db.
As for comparing two video cards for noise purely based on supposition:
- usually two-fan cooled cards will be significantly noisier (think 10-15, maybe even 20 Db noisier)
- larger fan blades usually means they'll rotate a lot slower than smaller ones (2000 RPM or under) -> less noisier
- overclocked versions of graphic cards are usually noisier (they need more cooling to keep everything stable for the higher clocks -> bigger fans/ faster rotation)
I'm not sure which is the exact model of your GTX 560 ti (this matters because some models have 1 fan, some have 2, some have bigger blades, etc), but I'll take a wild guess...