After just two months on the market, Microsoft has quietly upgraded the processor inside their Surface Pro 2 tablet. The latest batch of units being sold at retail has seen the Intel CPU upgraded from an Intel 'Haswell' Core i5-4200U to a Core i5-4300U, which provides a few modest improvements.

Primarily, the base clock speed of the dual-core CPU has increased from 1.6 GHz to 1.9 GHz, with a comparable increase in Turbo clock speed from 2.6 GHz to 2.9 GHz. The maximum dynamic frequency of the Intel HD Graphics 4400 chip has also increased slightly, from 1.0 GHz to 1.1 GHz. Other specifications such as cache (3 MB), memory bandwidth (25.6 GB/s) and TDP (15 watts) remain the same.

For what it's worth, extra CPU features include vPro, VT-d, TSX-NI, Trusted Execution Technology and a few other enterprise-related bits and pieces. Whether software will take advantage of these extra features is another story.

It's not clear why Microsoft upgraded the processor in the later models of the Surface Pro 2, with the company declining to provide specifics when contacted by The Verge. "Microsoft routinely makes small changes to internal components over the lifetime of a product, based on numerous factors including supply chain partnerships, availability, and value for our customers," a spokesperson said.

Reports indicate the change was made sometime in late December, with most future stock set to include the i5-4300U out of the box.