Proxmox electricity saving – 5 tips

Rising electricity costs are making it increasingly important to act in an energy-efficient manner – even in IT. If you use Proxmox as a virtualization platform, you can take targeted measures to save electricity without having to sacrifice performance. Especially small servers in home networks and home labs that run around the clock can become a power and therefore money guzzler. In this article, I will show you practical tips on how you can save electricity with Proxmox and reduce your ecological footprint at the same time.

In advance: Measure power consumption

To make the effects of our measures visible, we should first measure power consumption before optimizing power consumption. An inexpensive measuring device* or a smart socket such as the TP-Link Tapo P110 is sufficient for this.

Proxmox electricity saving: 5 tips

The 5 tips for saving Proxmox power cover the purchase of hardware, BIOS settings and software settings in Proxmox itself.

The right hardware

Of course, the right choice of hardware is the basis for optimizing the energy consumption of Proxmox. Old enterprise hardware often has a high idle consumption of 200 watts or more. It is therefore better to look at consumer hardware. Mini PCS are particularly suitable, as they often score with an idle power consumption of only 15 to 20 watts. However, the expansion options are very limited.

You should also pay attention to the power consumption of expansion cards. For example, the Intel X520-D2 10Gbit network card alone consumes 8.6 watts. This affects the Proxmox power consumption.

In the Hardwareluxx forum there is a list of particularly energy-saving configurations for Proxmox.

In general, it depends on all components: Starting with the power supply unit, which has a certain level of self-consumption. There are also different efficiency levels such as bronze, silver, gold and platinum.

Components that tend to indicate high power consumption are

• Graphics cards
• RAID Controller / HBAs
• Network cards with more than 10 GBit speed

Set BIOS settings correctly

Deactivate unnecessary hardware

Most BIOS / UEFI offer the possibility to deactivate certain hardware. With a virtualization host, for example, the audio chip is often not required. The same applies to unused PCie devices, COM ports and USB ports.

Activate ASPM

ASPM (Active State Power Management) is a technology used in computers to optimize the energy consumption of PCIe (Peripheral Component Interconnect Express) connections. PCIe is a high-speed interface that is often used to connect hardware components such as graphics cards, SSDs or network cards.

How does ASPM work?

ASPM automatically switches between different power states, depending on the load and the requirements of the system.

Power states with ASPM:

1. L0 (Active State): The normal operating state with full power.
2. L0s (Low-Power Substate): A low-power state in which the connection is partially disabled to save power.
3. L1 (Low-Power State): A deep sleep state in which the connection is almost completely switched off to further reduce consumption.

The change takes place automatically and in milliseconds so that the performance of the system is not affected. ASPM should therefore always be activated in the BIOS.

Activate CPU power saving functions

The CPU also offers powerstats, in this case called C-Stats. Depending on the manufacturer and version, you should be able to activate up to C10. However, it is also possible that the options only go up to C6. However, you won’t save much power here.

What are C-States?

C-states are energy-saving modes for processors that help to reduce power consumption when the CPU is not fully utilized. Each C-state represents an energy-saving state, with C0 being the active mode and higher C-states (e.g. C1, C2, C3) representing lower energy-saving modes. In these states, parts of the CPU are deactivated or put into sleep mode to save energy.

In combination with Proxmox, you can save power by activating C-States in the BIOS and the right CPU management to ensure that your server works particularly efficiently without impairing performance under load. Here is a detailed list of common C-States and their functions:

C0 – Active State

• Description:
  The active operating state of the CPU in which it performs calculations.
• Energy consumption:
  Highest consumption, as all CPU cores are active.
• Application:
  Used when applications or processes are running.

C1 – Halt State

• Description:
  The first energy-saving state in which the CPU is no longer performing active tasks but is ready to resume work immediately.
• Energy consumption:
  Reduced compared to C0, but minimal.
• Application:
  Short-term idle states.

C2 – Stop Clock State

• Description:
  A deeper energy-saving mode in which the CPU stops the processor clock to save energy.
• Energy consumption:
  Lower than in C1, with slightly longer wake-up time.
• Application:
  For longer, but not permanent idling phases.

C3 – Sleep State

• Description:
  In this state, the internal CPU logic is deactivated while the cache content is retained.
• Energy consumption:
  Significantly lower than in C2, but with a longer response time.
• Application:
  For longer idle times, e.g. between computing-intensive tasks.

C4 – Deep Sleep State

• Description:
  A deep sleep state in which both CPU logic and voltage are further reduced. The cache is retained.
• Energy consumption:
  Very low, but with a noticeable delay when reactivating.
• Application:
  For systems that are not actively used for a longer period of time.

C6 – Deep Power Down State

• Description:
  In this state, the CPU is switched off almost completely. Voltage and cache content are also removed.
• Energy consumption:
  Extremely low, the lowest consumption among the standard C-States.
• Application:
  Maximum energy saving, especially in servers or systems that are only used sporadically.

Activate GPU power saving functions

The efficient use of GPU power states is an important step towards saving energy, especially when Proxmox is used as a hypervisor. GPUs from Nvidia and AMD have so-called power states that dynamically adapt power consumption to the workload. But what does this look like under Proxmox?

Power States and Proxmox

In Proxmox, the power states of a GPU can only be managed if the GPU is assigned to a virtual machine (VM) via GPU passthrough. If the GPU is not actively used by a VM, it often remains in the so-called “idle state”, in which significantly more power is consumed. This is because without an active VM, the GPU cannot switch to the energy-saving modes that are normally controlled by the drivers of the VM’s operating system.

The power states of GPUs (both Nvidia and AMD) are special operating modes that are designed for energy efficiency and performance. They adapt the clock rates and voltages of the GPU to the current workload. Here is a brief overview:

Nvidia Power States (P-States)

• P0: Maximum performance. This state is used for demanding tasks such as gaming or GPU rendering.
• P1-P8: Different power levels, depending on the workload. For example, for less intensive applications or partial load.
• P8-P12: Energy-saving modes that are activated during idle or low activity. The GPU clocks down to a minimum here.
• Adaptive Mode: Nvidia GPUs dynamically switch between P-States based on the load.

AMD Power States (PowerPlay States)

• DPM (Dynamic Power Management) States: Different power levels that adjust automatically:Polylang placeholder do not modify
  • D0: Full power, activated at high load.
  • D1-D3: Graduated energy-saving modes that are used in partial load or idle situations.
• ZeroCore Power: A special mode in which the GPU is almost completely switched off when the screen is in standby.

Similarities

• Boost mode: Both manufacturers offer boost technology (Nvidia GPU Boost, AMD Boost Clock), which temporarily raises the clock rate above the nominal limit with sufficient cooling and power supply.
• Idle mode: Minimum power consumption when there is no significant load.

The Power States help to optimally balance energy consumption, heat development and performance.

High power consumption without VM

If the GPU in Proxmox is not bound to a VM, it remains in a standard mode with higher power consumption. This leads to an increase in energy consumption even if the GPU is not actively used. This problem has also been discussed in the Proxmox forum.

Save power with GPU passthrough in Proxmox

To save electricity with Proxmox, you should note the following:

1. Assign the GPU to a VM: This is the only way the VM can control the power states of the GPU.
2. Ensure that the GPU drivers are installed correctly in the VM: This allows the GPU to switch to energy-saving mode (e.g. P8 for Nvidia or ZeroCore for AMD) when it is not needed.
3. Check the GPU passthrough settings: An incorrect configuration can cause the GPU and thus the Proxmox server to consume an unnecessary amount of power.

A way to automate the whole thing was also found in the forum.

Save energy with a dummy VM for GPU Power States under Proxmox

If the VM assigned to the GPU is only used occasionally, it can be useful to control the power states via a dummy VM. This is started automatically when the main VM is shut down. Because the drivers are installed, the GPU can be set to a low power state.

Step 1: Set up dummy VM

Create a VM in Proxmox

• Resources: 512 MB RAM, 2 CPU cores, 4 GB memory.
• Operating system: Debian (e.g. Debian Bookworm).

Add the GPU as a PCI device

• Navigate to your dummy VM in Proxmox.
• Go to Hardware > Add PCI device and select the GPU.

Configure Debian

Open the file /etc/apt/sources.list

nano /etc/apt/sources.list

Add the following repository:

deb http://deb.debian.org/debian bookworm main contrib non-free non-free-firmware

Update the package sources and install the Nvidia drivers:

apt update
apt install nvidia-smi

Restart the VM:

reboot

Step 2: Create hookscript

The hook script ensures that the dummy VM starts and stops automatically, depending on whether the main VM is active.

Switch to the directory for hook scripts:

cd /var/lib/vz/snippets

Create and make the script executable

touch nvidiavm.sh
chmod +x nvidiavm.sh
nano nvidiavm.sh

Insert the following content (adjust the VM IDs):

#!/bin/bash
VMID=$1
PHASE=$2

if [ "$VMID" = "105" ]; then
  if [ "$PHASE" = "pre-start" ]; then
    echo "Win10 VM pre-start: Stopping Nvidia Dummy VM"
    qm stop 200

  elif [ "$PHASE" = "post-stop" ]; then
    echo "Win10 VM post-stop: Starting Nvidia Dummy VM"
    qm start 200
  fi
fi

• VMID 105: The ID of the resource-intensive VM.
• VMID 200: The ID of the dummy VM.

Save the file with CTRL + X and “Y”

Step 3: Assign hookscript to the main VM

Bind the script to your performance-intensive VM:

qm set 105 --hookscript local:snippets/nvidiavm.sh

Start and stop the main VM. Check the execution of the hook script with :

journalctl -b

You should see entries like this one:

Jul 29 01:53:48 deb qmeventd[135980]: Win10 VM post-stop: Starting Nvidia Dummy VM

With this setup, your GPU remains in a power-saving state even when idle. The dummy VM ensures that the Nvidia drivers remain loaded while the hookscript takes over automatic control.

Reduce CPU clock to save power with Proxmox

Proxmox disables all power-saving functions by default to ensure maximum performance. However, with a few adjustments you can lower the CPU clock rate and thus save power efficiently with Proxmox. Although these changes are not officially supported, they work without any problems. Note, however, that your system may react a little slower, as components must first be “woken up” from energy-saving mode.

Check CPU mode

You can use this command to find out which mode your CPU is working in:

cat /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor

Each CPU core is listed individually here. By default, the mode is set to “performance”. If you want to see the current frequency of the CPU cores, enter :

cat /sys/devices/system/cpu/cpu*/cpufreq/scaling_cur_freq

Set the CPU to energy-saving mode

To make the CPU more efficient and reduce the clock rate, you can set the “scaling_governor” to “powersave”:

echo "powersave" | tee /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor

This lowers the frequency of the CPU cores and helps you to save power with Proxmox. However, this value is reset to the default value after a restart or update.

Save setting permanently

To keep the energy-saving mode active after a restart, you can enter the command in the crontab:

Open the Crontab with :

crontab -e

If you are asked which editor you would like to use, select “nano”. Press “1” on the keyboard. Add the following line to the bottom of the crontab file:

@reboot echo "powersave" | tee /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor

Save the file with CTRL+X and confirm the changes with “Y” for Yes.

Check settings

After a restart, you can use the above commands to ensure that the CPU cores are running in energy-saving mode. For example, shows you:

cat /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor

whether all cores are set to “powersave”.

With these adjustments, you can reduce the CPU clock rate and effectively save power with Proxmox. Even if the system reacts a little slower as a result, you will benefit from lower energy consumption – ideal for environments where efficiency is paramount.

Proxmox offers numerous ways to reduce the energy consumption of your infrastructure and work more efficiently. By using modern, energy-saving hardware, optimized BIOS settings such as ASPM (Active State Power Management) and deactivating unnecessary devices, you can already achieve significant savings. In addition, power consumption can be further reduced with the right CPU power governor. With the GPU passthrough trick, you can even increase the energy efficiency of GPUs by actively using power states.

Why saving electricity with Proxmox makes sense

Saving electricity not only pays off financially through lower energy costs, but also protects the environment. Especially in times of rising electricity prices and growing environmental awareness, an energy-efficient IT infrastructure is a decisive advantage. With the right settings, you can reduce operating costs and make a contribution to sustainability at the same time – without sacrificing the benefits of Proxmox.

With these measures, you can save Proxmox electricity and create an efficient, environmentally friendly IT solution.