Overall though, Intel is promising 2X to 3X speedups, and only for software that lends itself to parallelization and vectorization. According to Joe Curley, Intel's director of marketing for the Data Center Group, that entails a relatively small portion of HPC applications. "But," he says, "customers who have those applications are motivated to find ways to get performance breakthroughs."

Intel has to thread the needle here. It can't tout the Xeon Phi at the expense of its mainstream Xeon CPUs. The idea is to speed up applications or portions of applications that are out of reach for straight Xeons. But the chipmaker wants to sell you both products -- one for maximizing single-threaded codes, the other for highly parallel, vector-intensive ones. That's not really different from how NVIDIA has positioned its GPU accelerators relative to CPUs.

NVIDIA, though, is more aggressive about pointing to big performance increases over CPU-only platforms, more on the order of 5X to 30X and beyond. For its new K20X Tesla part announced earlier today, the GPU-maker is claiming a 7X performance advantage over to a Sandy Bridge Xeon. Although that makes it seem like the GPU competition is three times faster than Knights Corner, the NVIDIA comparison is GPU-to-CPU, while Intel prefers to match its coprocessor against two Xeons.

Nevertheless, NVIDIA's K20 does top Knights Corner in both raw performance and performance per watt. The 235 watt K20X offers 1.31 double precision teraflops, while the 225 watt 5110P, at 1.011 teraflops, delivers 300 gigaflops less. Advantage NVIDIA.

The Gen1 demo, on display at SC12, was real silicon, and engineering samples for the Gen2 device are due out this summer. If all goes as planned, the Hybrid Memory Cube will be in full production at the end of this year or early 2014. In fact, contracts are already in place for the 2014 timeframe.