I can confirm I too have the artifact problem out of the box. Relieved to see there's a vBIOS update to rectify the problem, update the vBIOS from 15.39 to 15.41 with the same results, tried driver versions 13.12 from ATI and from ASUS, tried 14.1 beta with the same results.
RMA it at the store, got a 1 to 1 replacement. Out of the box came with vBIOS 15.41, tried drivers 13.12. Sadly artifacts still persist. Worried that it might be problems with other hardware since 2 GPU came with the same problems. Happy and sad at the same time when I discovered many people also face the same problems, in the end with so many complaints and the fact that ASUS release a BIOS update that suggest to solve the artifacts issue, it is my opinion that it is a GPU problem.
Strangely most reviews I've read before getting this card didn't mention anything about this. Now I'm required to bring back the GPU to the store for them to troubleshoot the problem, I hope they see it as well otherwise I'll have to live with this defect and I'll probably get a refund or go with NVIDIA, I'm just tired with AMD already.