Hello,
 
after 2 weeks waiting i just got my new GTX 780 SC ACX.
after i booted into windows i noticed slightly rattling noises from the fan.
after playing a game when exiting back to windows i also noticed often louder fan noises (rattling or grinding type)
i bought this card because it was supposed to be with the less noisiest cooling solution.
I previously had a GTX680 from EVGA whoch never made such noises.
What can i do now:
1. return to my etailer and buy a new one(bad option because availability is still very bad for this card)
2. go through RMA with etailer or vega (how long will this take??)
3. wait and see if the noises maybe go away?
 
any ideas?
 
Regards,
P.
 
 

RMA while they have replacements available ....

They have none at the moment.
shop says next shipment will arrive end july

eVGA online shop?  They have been available for the past 8 hours ....

Mine has bad resonance. If I increase the fan speed using Precision to 43-44% the noise drops to tolerable. I've had the card for a week, I'm waiting for the fan speed update that will allow us to go to 33%. If that does not fix it, or the noise does not improve, I'll be returning the card to my retailer. This card costs way too much to have this sort of problem IMO. Sadly, I love everything else about it.

Maybe a stupid question but did you remember to remove the clear plastic film from the card around the fans?

Just wanted to add that i'm having EXACTLY the same issue as described here.
780 SC ACX 
When i boot into windows and i'm just idling at desktop, there is a very irritating and very noticable rattle coming from the fan nearest the power connectors on the card.
 
This fan is idling at 39%, if i set it to 41% or above then the rattling disappears.
 
Is there any way to edit the bios to 41% the minimum fan speed ?

SLICKRIC21

This fan is idling at 39%, if i set it to 41% or above then the rattling disappears.
Is there any way to edit the bios to 41% the minimum fan speed ?

Install Precision... set fan profile minimum to 41% or higher. 

I have exactly the same problem!! resonance at 39% fan speed
I fixed it by setting min fan speed at 41% via precision software, but there is a second resonance sound around 52% fan speed.
This is just unacceptable for such an expensive product!

Mine does it too.. but its very easy to get rid of it unlike the 600 series where i had to RMA the card.