IBM and Microsoft, which alternate between fierce competitors and willing partners, are teaming up to test new limits in the field of high-performance computing and the cloud.

On June 27, IBM officially will announce that Microsoft is one of the first customers for its iDataPlex server array. IBM first introduced this x86 server system in April as a way to build out an enterprise’s infrastructure for cloud computing, Web 2.0 applications and high-performance computing.

In the case of Microsoft, the company’s Windows Server Group plans to use a data center full of iDataPlex systems to test and benchmark its high-performance computer cluster operating system called Windows HPC Server 2008. For years, the field of HPC and supercomputing has been dominated by systems running Linux, and Microsoft is looking to change that. It recently announced that it had helped construct a system that offers a performance of 68.5 teraflops, or 68.5 trillion calculations per second.

While the rivalry between Microsoft and IBM has been fairly intense in certain areas, the two companies also need each other, and this agreement helps the two in very different ways.

For Microsoft, the deal allows it to tap into the expertise and success that IBM has within the HPC and supercomputing field. In the latest version of the Top 500 supercomputer list, IBM had five machines in the Top 10, including the $100 million Roadrunner system at the Los Alamos National Laboratory, with a performance of more than 1 petaflop.

The iDataPlex, which uses a number of commodity parts—from Intel processors to industry-standard switches—allows Microsoft to use that expertise in its own internal testing of its OS. (The IBM iDataPlex also uses Linux as part of its commodity makeup—a point IBM makes in its announcement. However, a spokesperson for Big Blue said iDataPlex can run both Linux and Windows, since it's based on x86 hardware.)

To help with HPC, IBM is also expanding iDataPlex with Intel Xeon quad-core 5400 series processors—3.0GHz—to pack 145 teraflops of performance into one of the company’s new 315-square-foot modular data centers.

“It’s a very practical platform for Microsoft to test on and help configure the operating system,” said Charles King, an analyst with Pund-IT Research. “To test in an HPC environment, a company needs systems that can scale and can [be] very dense, and I think Microsoft is well-served by using something like iDataPlex.”