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How to Install SteamOS 3.9.5 on a Regular PC: Step-by-Step Guide

Updated: 24.10.2026 · AI Release · @ai_release1
How to Install SteamOS 3.9.5 on a Regular PC: Step-by-Step Guide

TL;DR

Requirements and setup

Illustration: Requirements and setup
Illustration: Requirements and setup

Checklist before you touch anything:

Unknowns to verify against the documentation: the exact file name of the 3.9.5 image, the list of officially supported GPUs and Wi-Fi chips, and whether the image you downloaded is a full installer or a recovery image. Read those on the official SteamOS page before you start — this guide does not reproduce file names or URLs it cannot confirm.

If the target machine will keep a Windows 11 installation on another disk, apply pending Windows updates first, as described in this manual update walkthrough, so an unfinished update does not interfere with the boot entries later.

Step 1. Write the SteamOS image to the USB drive

Illustration: Step 1. Write the SteamOS image to the USB drive
Illustration: Step 1. Write the SteamOS image to the USB drive

What to do: decompress the image, verify its hash, then write it to the raw USB device.

Why: the SteamOS image is a complete disk image (partition table + EFI system partition + root filesystem). Copying the file to a mounted USB stick produces an unbootable drive; only a byte-for-byte write to the raw device works.

How to check: after writing, the USB drive must show a GPT partition table with an EFI system partition.

Identify the USB drive first — this is the step people skip and regret:

lsblk -o NAME,SIZE,MODEL,TRAN

Example output (yours will differ):

NAME   MAJ:MIN RM   SIZE RO TYPE MOUNTPOINTS
sda      8:0    0 465.8G  0 disk
└─sda1   8:1    0 465.8G  0 part /
sdb      8:16   1  29.8G  0 disk

TRAN shows usb for the flash drive, and RM is 1 for removable media. On macOS the same device appears as /dev/disk2 — see diskutil list.

Decompress and verify:

bzip2 -dk <steamos-3.9.5-image>.img.bz2
sha256sum <steamos-3.9.5-image>.img

Replace <steamos-3.9.5-image> with the real file name from the download page. Compare the printed hash with the one published next to the download — they must match character for character. A mismatched hash means a corrupted download, and a corrupted image will fail mid-install, not now.

Write the image (replace /dev/sdb with your device — without a trailing digit):

sudo dd if=<steamos-3.9.5-image>.img of=/dev/sdb bs=4M status=progress oflag=sync conv=fsync

oflag=sync and conv=fsync force the kernel to flush every block before dd returns, so you do not unplug a drive that is still buffering. Expect it to finish without output beyond the progress line.

Verify the result:

sudo fdisk -l /dev/sdb

Example: you should see Disklabel type: gpt and a partition of type EFI System, several hundred megabytes in size. If fdisk shows a single FAT/exFAT partition, the write failed — repeat it.

Step 2. Boot the target PC from the USB drive and install SteamOS

What to do: boot the target PC from the USB drive, start the installer from the live session, and point it at the internal disk.

Why: the USB image boots a live Linux environment; the installer is what actually partitions the internal drive and copies the system onto it. Nothing is written to the internal disk until you confirm the target.

How to check: before confirming, the installer must show the same disk model and capacity you identified earlier.

1. Insert the USB drive, power on, and press the boot-menu key repeatedly. Pick the entry prefixed with UEFI: — a non-UEFI entry will not boot the image.

2. The live environment loads to a desktop. Open a terminal and confirm which disk is internal:

lsblk -d -o NAME,SIZE,MODEL

Example: /dev/nvme0n1 with 476.9G and your SSD's model name is the internal drive; /dev/sda with roughly the USB capacity is the stick. Write the internal device name down.

3. Start the installer entry the image provides. Its exact label depends on the image type — on a full installer it is a boot-menu entry, on a recovery image it is a desktop icon whose action is described as re-imaging. If the label does not match either description, check the official installation documentation before proceeding.

4. Select the internal disk from step 2 as the target and confirm the erase. Everything on it is destroyed at this point.

5. Wait for the copy to finish and reboot. Remove the USB drive when the screen goes dark, otherwise the PC may boot from the stick again.

Example of a successful run: the installer reports completion, the machine reboots without the stick, and you land in the Steam Deck-style Game Mode interface rather than a firmware menu or a GRUB prompt.

Step 3. Verify the installation

Illustration: Step 3. Verify the installation
Illustration: Step 3. Verify the installation

What to do: confirm the system boots on its own, runs the expected version, and that the boot entry and network are healthy.

Why: a first boot can succeed while the EFI boot entry or the network stack is broken — those failures only appear after the next reboot or the first Steam sign-in.

How to check: run the commands below inside Desktop Mode.

Switch from Game Mode to the desktop:

steamos-session-select desktop

steamos-session-select is the session switcher shipped with SteamOS; steamos-session-select gamescope returns you to Game Mode.

Check the release:

cat /etc/os-release
uname -r

Example: /etc/os-release contains a NAME line naming SteamOS and a VERSION_ID line naming the 3.9.5 build; uname -r prints a kernel version. If NAME reports a different distribution, you booted the wrong device.

Check the boot entry survived:

efibootmgr -v | head -n 20

Example: an entry containing steamos in its label, listed in BootOrder. If it is missing from BootOrder, the firmware will fall back to another OS on the next cold boot.

Check the network:

ip -brief address

Example: your Wi-Fi or Ethernet interface (wlan0, enp3s0) shows an UP state with an IPv4 address. With no address, sign in to Wi-Fi from the desktop tray before launching Steam.

Final acceptance: reboot once with no USB attached, confirm you reach Game Mode unaided, then launch one installed game or a Steam client sign-in screen. A clean second boot is what separates "it installed" from "it works".

Once the machine is stable, it is a normal Linux box — the walkthrough in How to add AI to your home server applies to any self-hosted service you want to run on it.

Troubleshooting

Problem. The USB drive never appears in the boot menu, or the firmware refuses it.

Problem. dd stops immediately.

lsblk -o NAME,SIZE,TRAN
sudo dd if=<steamos-3.9.5-image>.img of=/dev/sdb bs=4M status=progress oflag=sync conv=fsync

Problem. Package operations fail after installation.

sudo steamos-readonly disable
sudo pacman -Syu

Note that a system update can revert changes made outside the image's own update path — check the official documentation for the supported way to persist them.

Summary and next steps

You now have SteamOS 3.9.5 booting from the internal disk of a regular PC, with a verified image, a verified EFI entry and a working network. Next, check the official supported-hardware list for your GPU and Wi-Fi chip, then install your games and, if you need more from the machine, add self-hosted services on top of it.

FAQ

Will installing SteamOS erase my Windows installation?

The installer writes to the entire disk you select, so every partition on that disk is destroyed. Assume no dual-boot is preserved unless the official documentation explicitly states otherwise for your image.

Do I need a Steam Deck to install SteamOS on a PC?

No — the image boots on generic UEFI x86 hardware. Hardware support (GPU, Wi-Fi, audio) varies by model, so verify your components against the official supported-hardware list.

How do I switch between Game Mode and Desktop Mode?

Run steamos-session-select desktop from a terminal in Game Mode, and steamos-session-select gamescope from the desktop to go back.

How do I know the downloaded image is intact?

Run sha256sum on the decompressed .img and compare it with the hash published on the download page. A mismatch means re-download, not re-flash.

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