Member Avatar for Mushy-pea

Hi. In August I built a PC using a second hand Biostar TA990FXE "Extreme Edition" motherboard and AMD FX-6100 six core CPU @3.3 GHz at the core of it. I recently installed the Oracle Virtualbox VM on Windows 10 and tried running a couple of Linux and BSD OS instances, during which I noticed that task manager was reporting (at times) the CPU clocking at up to 3.87 GHz (or ~17% over the quoted maximum). Note that over clocking options were disabled in the BIOS at the time. I am just curious as to whether this is due to the VM using hardware virtualisation and some feature of the CPU or motherboard detecting this and increasing the clock speed limit. Has anyone seen this kind of behaviour on your own systems?

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  • Latest Post Latest Post by rproffitt

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Short answer: that reading is expected — the FX‑6100 is a Turbo/Core‑boosting part (3.3 GHz nominal, up to about 3.9 GHz), so Task Manager showing ~3.87 GHz is consistent with the chip running a boost state rather than a permanent manual overclock. (techpowerup.com)

Why it happens: AMD Turbo Core (aka Core Performance Boost) raises the frequency of busy cores when thermal/power headroom and inactive cores permit; VM workloads (or the way the host schedules VM threads) can create short periods where one or a few cores run hot and get boosted. The FX‑6100 also supports hardware virtualization, so a VM can drive that behaviour. (anandtech.com)

BIOS caveat: Biostar boards sometimes include an "auto overclock" helper separate from the manual OC menus. The TA990FXE UEFI exposes an Overclock Navigator / Auto OverClock System (with preset engines) and PowerNow/ACPI options — check those entries even if you believe "overclocking" was off. Disable Overclock Navigator (and any "Auto OC" or "V6‑Tech" engine) to rule out motherboard-driven boosts. (manualslib.com)

How to confirm (quick checklist + commands/tools):

  • Windows: run CPU‑Z or HWMonitor to watch real‑time core speeds while starting the VM (CPU‑Z shows core speed and multiplier). (cpuid.com)

  • Linux: use cpupower/cpufreq or the sysfs interface to observe current/boost frequencies:

    # show current MHz (quick)
watch -n 1 "grep 'cpu MHz' /proc/cpuinfo | head -n 6"

# or use sysfs (values in kHz)
watch -n 1 "cat /sys/devices/system/cpu/cpu*/cpufreq/scaling_cur_freq"

# or get policy/boost info
cpupower frequency-info

    (kernel cpufreq docs explain these interfaces). (kernel.org)

If you need a forced baseline for testing: disable any BIOS auto‑OC features and (optionally) disable Core Performance Boost in BIOS, then recheck frequencies. Also update the TA990FXE BIOS to the latest stable build and verify adequate cooling/power — Turbo behavior is gated by power/thermal headroom as well as BIOS policy. (manualslib.com)

Note: was on the right track pointing to Turbo; for the above checks will show whether you’re seeing stock Turbo behavior or an unintended board-level auto‑overclock.

Member Avatar for rproffitt

notes it's Turbo Clock Speed.
asks a few more questions.

To your last question. Yes.

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