It took me just over a week from when it died and I shipped next day to them after a conversation with a tech on their phone service. This was a 939 but it shouldnt matter.
Ive found Asus in the US to have one of the better Service/RMA depts. Just call them and foot the phone bill, emails seem to add time(days) to the RMA process.
Thay also have the policy that if something happens in shipping and the RMA ends up DOA, they then pay to ship both ways!!!
Although, I've found that having them help you through a troubleshoot through e-mail will cut RMA time if you enclose the case number from the email corrspondence; there's less troubleshooting that they have to do on their end once they recieve your part. Last mobo I RMAed through ASUS I had back within a week thanks to that - I payed for priority shipping there and had a board back by the end of the week.
Although, I wasn't all that happy with what I recieved back - and I promptly told them so. The mobo I had sent in for failed temp sensors was 2 weeks old out of the box, and still had that brand new look. The unit I was returned looked like it had been around a while, "gently used" I guess you could say . . . there was even a difference as to where the two were manufactured (go figure the faulty one was made in Taiwan and the one I was returned was made in China). I wasn't happy about it due to the aesthetics, and I let them know, but didn't push for a different board - I didn't see a point, truthfully.
Awesome company as far as customer relations, though - from my experiences, they do their best to help you get to the root of the problem instead of just immediately pointing the finger at some other component; plus, if you make sure to inform them of your technical level, they deal with you as such (frustrating for most of us that are fairly knowledgable to be dealt with like we're n00bz).