We present a cost - effective scalable real - time wavefront control architecture based on off - the - shelf graphics processing units hosted in an ultra - low latency , high - bandwidth interconnect PC cluster environment composed of modules written in the component - oriented language of nesC. The architecture enables full - matrix reconstruction of the wavefront at up to 2 KHz with latency under 250 us for the PALM-3000 adaptive optics systems , a state - of - the - art upgrade on the 5.1 meter Hale Telescope that consists of a 64 x 64 subaperture Shack - Hartmann wavefront sensor and a 3368 active actuator high order deformable mirror in series with a 241 active actuator tweeter DM . The architecture can easily scale up to support much larger AO systems at higher rates and lower latency .