  As users and developers, we are witnessing the opening of a new computing
scenario: the introduction of hybrid processors into a single die, such as an
accelerated processing unit (APU) processor, and the plug-and-play of
additional graphics processing units (GPUs) onto a single motherboard. These
APU processors provide multiple symmetric cores with their memory hierarchies
and an integrated GPU. Moreover, these processors are designed to work with
external GPUs that can push the peak performance towards the TeraFLOPS
boundary. We present a case study for the development of dense Matrix
Multiplication (MM) codes for matrix sizes up to 19K\times19K, thus using all
of the above computational engines, and an achievable peak performance of 200
GFLOPS for, literally, a made- at-home built. We present the results of our
experience, the quirks, the pitfalls, the achieved performance, and the
achievable peak performance.
