SteamOS 3.8 on ROG Ally X: FPS Gains, TDP Tweaks, and Battery Life

SteamOS 3.8 delivers impressive stability and performance on the ROG Ally X with Z1 Extreme APU.

Hardware by Katmin on Oct 01, 2025

SteamOS 3.8 is now running on the ROG Ally X using the official Steam Deck recovery image. Unlike other custom distributions, such as BazziteOS, this is the true SteamOS, directly from Valve.

Running on the Z1 Extreme APU, the performance is impressive, especially at lower TDPs around 15W. The Ally X has an 80Wh battery, which gives it great battery life that beats the Steam Deck's in similar settings.Installation and SetupIt's easy to install SteamOS 3.8 on the ROG Ally X. We utilized the recovery image from Valve's Steam Deck and then switched to the main branch beta for full functionality. Currently, there are some limitations, including the absence of RGB control and non-functional front ROG buttons.

However, Valve has already announced plans to release a beta of SteamOS optimized for more handhelds in the future.

SteamOS 3.8, ROG Ally X, FPS Gains, TDP Tweaks, Battery Life, NoobFeed

System Settings and TDP Control

SteamOS 3.8 provides VRR support on the Ally X's 120Hz display. Out of the box, the TDP defaults to 18W but does not display correctly in the system menu. To gain full control, we utilized Decky Loader with the Simple TDP Control plugin, which is compatible with ASUS hardware.

This allows TDP adjustments between 4W and 40W. For most scenarios, we recommend 15W to match the Steam Deck, although increasing to 20W unlocks significantly better performance.

Cyberpunk 2077 Testing

Running Cyberpunk 2077 at 800p with the Steam Deck preset at 15W yields a minimum of 36fps and an average of just over 40fps. Increasing the TDP to 20W and raising resolution to 900p pushes performance over 60fps while still offering strong battery life thanks to the larger 80Wh battery.

Comparisons With the Steam Deck OLED

Benchmarks show big disparities between the Ally X and the Steam Deck OLED:

Shadow of the Tomb Raider (15w TDP)
Steam Deck OLED: 58 fps on average and about 25 watts of battery power.
Ally X: 64 fps on average and about 23 watts of power use
Cyberpunk 2077 (15w TDP)
Steam Deck OLED: 44fps
Ally X: 53fps

The Ally X always works a little better and uses less power. Its bigger battery also means it lasts longer. That being said, the Steam Deck OLED is still better for independent games, using 3 to 4 watts less power on average.

SteamOS 3.8, ROG Ally X, FPS Gains, TDP Tweaks, Battery Life, NoobFeed

Additional Game Testing

Spider-Man 2 (20w TDP, low settings, FSR on): It works well in either 720p or 900p, depending on what you want.
Kingdom Hearts 3 (1080p medium, 15w): Easily maintains over 60fps.
The Witcher 3 (900p Steam Deck preset, 18w): Delivers consistent performance with only slight dips at lower TDP.
Doom Eternal (900p low, 15w): Exceeds 60fps even at modest wattage.
Fallout 4 (16w): Runs at near 60fps, with occasional drops to 58fps.
Street Fighter 6 (900p medium, 15w): Stable 60fps in SteamOS compared to needing 17w in Windows.
Monster Hunter Wilds (720p low with frame gen, 28w): Playable around 45-60fps depending on conditions.
Hades II (battery test): Steam Deck OLED draws less overall wattage, highlighting its efficiency advantage.

Optimizations and Future Potential

While the Ally X lacks RGB and ROG button support in SteamOS, Decky Loader plugins fill many gaps. The Z1 Extreme APU is clearly capable of higher performance when the TDP is raised. The combination of 24GB RAM (with up to 12GB assignable to VRAM) and the lightweight nature of SteamOS makes this handheld extremely flexible.

We can expect further optimizations when Valve releases its official SteamOS beta for handhelds. At that point, the Ally X and similar devices may benefit from improved power efficiency and expanded compatibility.

SteamOS 3.8, ROG Ally X, FPS Gains, TDP Tweaks, Battery Life, NoobFeed

Final Thoughts

Running SteamOS 3.8 on the ROG Ally X shows promising results. It has great performance that goes from 15W to 40W, a long-lasting battery thanks to its 80Wh pack, and it works with Decky plugins for system control. This makes it a real competitor to the Steam Deck.

Valve's handheld is remains the best choice for indie developers, but the Ally X's extra space, bigger battery, and Z1 Extreme capability make it a great choice for people who want greater performance without losing portability.

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