The unlocked Broadwell desktop processors due mid-year could turn out to be potent overclockers. According to a report at EXPreview, at least one chip circulating in Asia is capable of 5GHz on air. That frequency is higher than what we've managed with our Haswell CPUs, including the most recent Devil's Canyon chips. Only 1.42V was apparently required to hit the mark.
All the actual overclocking was done by Hong Kong site HKEPC, which posted a series of images to its Facebook page showing a purported Core i7-5775C processor running in Gigabyte and ASRock motherboards. That photo stream includes a handful of benchmark and CPU-Z shots, but oddly, they all depict the processor at what is presumably its default frequency. The CPU-Z shots showing the chip at 4.8 and 5GHz only appear at EXPreview. They don't appear to be faked, though. HKEPC may have simply removed those images from Facebook.
If the results are legit, they still represent a single sample. There's no guarantee that all unlocked Broadwell chips will hit similar speeds—or get into the same territory with such a low voltage and modest cooling.
The Core i7-5775C hasn't even been formally announced, but we at least know something matching its description is coming. Intel confirmed at GDC that socketed Broadwell chips are due in the middle of the year. They'll have unlocked multipliers, Iris Pro integrated graphics, and relatively modest 65W thermal envelopes. That low TDP could be the key to the chips' overclocking potential.