San Francisco, Aug 16 (IANS): Some Microsoft Surface Pro 6 and Surface Book 2 devices are throttling down to crippling low speeds of 400MHz, post the new firmware update that was rolled out on August 1.

The throttle-lock appears to be caused by an Intel CPU flag called BD PROCHOT (bi-directional processor hot), which can be set by any peripheral, telling the processor to throttle down to decrease system temperature, a report in the Tech Republic said on Thursday.

The issues were flagged by several users on Reddit.

However, along with the CPU issues, Microsoft's latest firmware updates have been causing Wi-Fi issues for several users.

Surface Book and Surface Pro 6 owners have complained on Microsoft's support forums that the latest Marvel Wi-Fi driver, supplied with Microsoft's Surface firmware updates on August 1, is not allowing devices to connect to some 5GHz wireless networks.

We experienced these issues on a Surface Pro 6 device, and the problems could be related to certain router combinations, the TechCrunch reported.

"If you have Wi-Fi issues on a Surface device since the updates earlier this month, you can simply roll back the driver in device manager, which will restore access to 5GHz networks. A Microsoft volunteer moderator claims the company is 'working on an update'," the TechCrunch report added.