Intel Speed Step reduces the CPU's performance
Intel Speed Step reduces the CPU's performance
Hi, I've noticed your friend's laptop is acting sluggish, especially when using battery mode. The Dell Latitude 7380 or 7390 with an Intel Core i5 8250U processor shows this issue only under low power settings. Even after changing the minimum processor state to 100%, it didn't help. The system still caps the CPU speed at 400MHz, and Windows Power Settings are set to keep the processor at full capacity while cooling is active. I adjusted the processor power management but saw no improvement. It seems the throttling might be coming from the BIOS or hardware limitations. Have you encountered similar problems before? You might want to disable Intel SpeedStep in the BIOS and see if that stabilizes performance, or consider checking the power adapter's condition. Let me know if you need more details!
A new setup of Windows is probably what you need. By default, Windows doesn’t handle this, so someone else must have done it.
It's interesting that the BIOS limits the CPU clock to 400MHz even though it runs at about 1.6GHz in battery mode. Starting in diagnostic mode also feels slower, and testing the CPU there takes more time. I suspect the problem isn't software-related but hardware-based. Turning off Intel SpeedStep restores the advertised speed. The system appears clean with minimal apps—except Microsoft Office, Firefox, Google Chrome, and some accounting tools—and none of them seem to be the cause. The BIOS is current and drivers are up to date. I think the issue might stem from Intel's Thermal Management Interface, though that’s uncertain. This behavior is definitely unusual for both Dell Latitude and Intel laptops.
Basically nothing can be done. Just turn off speedstep. It’s the worst thing. Even a YouTube video at 1080p feels like 10 frames per second on my XPS13 with an i7 running on battery. I dislike speedstep in these Dell laptops because it can’t be adjusted. Some users said DELL’s battery/performance tools might help, but they didn’t work for me or my machine.
I experienced the same problem, CPU remained at 0.4GHz regardless of settings. After rebooting and pressing F12 immediately, I initiated Preboot Diagnostics focusing on the fan. The fan test only lasted a brief moment, but I could detect its operation. I reinstalled Windows via the built-in start fresh feature while keeping files intact. Updated all drivers afterward. Added Dell Power Manager, applied high-performance thermal profile. Adjusted BIOS settings turning off SpeedStep and other turbo functions. Still no improvement. The solution came when I reset the BIOS back to defaults (re-enabling SpeedStep), disconnected from power, and followed the Dell service manual plus Ifixit instructions to remove the laptop’s back cover, unplugged the battery for a minute, then reinserted it. After restarting, Windows returned to normal operation.