Surface PCs hit with issue throttling CPUs down to 400MHz

Surface Pro 6 with Aqua keyboard
Surface Pro 6 with Aqua keyboard (Image credit: Daniel Rubino / Windows Central)

What you need to know

  • Recent firmware updates appear to have caused an issue that aggressively throttles the CPU on some Surface devices.
  • Both the Surface Pro 6 and Surface Book 2 seem to be affected, with CPU speeds throttled down to 400MHz.
  • Microsoft has acknowledged the issue and is working on a fix.

Microsoft's Surface Pro 6 and Surface Book 2 devices are suffering from a CPU throttling issue. According to user reports on Reddit, CPU speeds are being randomly throttled down to 400MHz.

"We are aware of some customers reporting a scenario with their Surface Books where CPU speeds are slowed," a Microsoft spokesperson said to TechRepublic in a statement. "We are quickly working to address via a firmware update."

What's causing the issue isn't apparent, but TechRepublic reports that it may have something to do with an Intel CPU flag called BD PROCHOT, which can be used to tell the system to throttle down when components become too hot. This flag is used on non-Surface devices as well, so it's presumed — but not certain — that recent firmware updates have introduced the issue to Surface Pro 6 and Surface Book 2 devices.

This throttling issue comes not long after Surface devices were reported to have an issue with connecting to 5GHz Wi-Fi networks following a driver update. Thankfully, there is a workaround for that issue. However, for CPU throttling problems, we'll have to wait to hear more from Microsoft on any potential fixes.

Dan Thorp-Lancaster is the former Editor-in-Chief of Windows Central. He began working with Windows Central, Android Central, and iMore as a news writer in 2014 and is obsessed with tech of all sorts. You can follow Dan on Twitter @DthorpL and Instagram @heyitsdtl

  • I have been getting this very same issue on my SPpro6 for the last 6 months. I have tried a number of times to get a resolution form MS support to no avail. It only happens when I have the power cord plugged in, when I notice the computer is going slow and check in task manager that the cpu is at 400mhz I just pull the cord out and it goes back to normal. Very annoying
  • I'm glad I read this now...I was almost ready to do a complete reinstall on my SP6 because I thought something was wrong with the the install.
  • I bought a Surface Book 2 since february and this has been going on since the minute I turned it on for the first time. When does it happen? When it's hot. when the pc gets hot? No, when it's hot outside. Clearly the surface book 2 thermals where not designed to work well when it's more than 75 degrees. the quick workaround is to change the power settings until it happens again, but the hotter it gets, the more frequently it will do it. I seriously believe this is a hardware design flaw, so the only solution at the moment is to turn on the AC.
  • Same thing is happening on my SP4
  • I actually have this problem on an HP ZBook Studio G4 (although it throttles down to 800mHz). I use a program called ThrottleStop to disable BD PROCHOT. The program also monitors CPU temperatures to make nothing gets too hot. I don't do anything on the device that ever maxes the CPUs so I am not worried about disabling this sensor causing the CPUs to get too hot.
  • I think I have the same issue for a few years now on my SP4, i5. Does your CPU clock speed drop down below 0.5 ghz? It happens randomly then everything freezes? Annoying as hell. It is especially bad when unplugged from charger...
  • The intel power management driver is not working properly. HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\intelppm
    1. At the right pane:
    a. Double click at 'Start' key.
    b. Modify the value data to '4'
    c. Click OK.
    d. Reboot Obviously use care here. And try to update your intel drivers first but this fixed a few surface pros and surface gos that were having this issue.