Recently with Intel's Sandy Bridge (I know I said I'd wait for the high-end Sandy Bridge-E at the end of this year but I couldn't wait), I bought two new rigs:
Prometheus
* ASUS P8P67 DELUXE (Socket 1155)
* Intel i7-2600k (3.4GHz Quad w/ HyperThreading)
* Corsair H70 (CPU cooling)
* Cosair Vengeance DDR3-1600 (16GB)
* AMD Radeon HD 6970 (2GB)
Atlas
* Asrock P67 Extreme4 (Socket 1155)
* Intel i5-2500k (3.3GHz Quad)
* Noctua NH-D14 (CPU Cooling)
* Corsair Vengeance DDR3-1600 (8GB)
* AMD Radeon HD 6870 (2GB)
I was able to overclock Atlas up to 4.6GHz (39.3% / 1.3GHz OC), with the RAM running at DDR3-2133 (33.3% / 533MHz OC) pretty easily on the Asrock motherboard and it's running stably on those settings folding away. Recently I swapped out the i5-2500k for a i7-2600k and am getting 4.7GHz (38.2% / 1.3Ghz OC), with the RAM running at DDR3-2133 (33.3% / 533MHz OC).
I had a lot of issues with Prometheus at first on the original the MSI P67A-GD65 motherboard I got initially since it seems to overvolt the CPU, so I never got a stable OC. I returned the MSI and got the ASUS P8P67 DELUXE and I couldn't have been happier. It's buzzing along at 4.9GHz (44.A% / 1.5GHz OC), with the RAM running at DDR3-2133 (33.3% / 533MHz OC) stably folding.
Haven't had time to overclock the GPU's yet, since I haven't had the time, but those components will not remain unturned for long!
I use Prometheus mostly for gaming, folding@home, and light infrastructure design using multiple VMWare Workstation virtual machines. I am in the process of consolidating my server farm onto fewer physical machines which run Xen virtual machines, which is what Atlas is being used for.