Was using your latest kernel with phoenix 2  rc1 on a cayman 6970 cat 12.3

New opencl version has built in support for uint3 so it might even work with your older version. It's basically just doing a typedef uint4 uint3, and it just assigns a 0 for last value of uint3 to ignore 'w'. The problem with your old kernel is you need to initialize uint3 as a uint4 first

Speed is good because you basically get to run vectors4 (vectors3) with less alu's. Even tho 'w' is not used finding x, y, and z nonces occurs much more frequently anyways