SteamOS on MSI Claw 8 EX: Intel Arc G3 Performance, CPU Clock Fix and XeSS Limits

The video is titled "We finally have official SteamOS booting straight out of the box on the MSI Claw EX AI+!" The handheld in it is powered by Intel's G3 Extreme CPU and Arc B390 graphics. For Windows handheld owners, the question is no longer whether SteamOS boots on this hardware. It's whether SteamOS is good enough to replace Windows 11 on it yet.

The hardware in question​

The Arc G3 Extreme is part of Intel's Panther Lake family, and it's aimed at the high end of the handheld market. Geeky Gadgets covered ETA Prime's earlier Windows review of the MSI Claw 8 EX. That review describes a 14-core CPU combining performance and efficiency cores, paired with the Intel Arc B390 GPU, which includes 12 Xe cores and supports advanced ray tracing. The same coverage lists an 8-inch 120 Hz VRR IPS display, 32 GB LPDDR5X RAM and a 1 TB NVMe SSD, along with an 80Wh battery.

It's an expensive device. VideoCardz, reporting on a cheaper configuration MSI just added, says the non-Extreme Arc G3 model comes in $300 below the $1,799.99 starting price quoted for the Arc G3 Extreme version. According to VideoCardz, the difference is mostly on the GPU side, with two fewer Xe3 cores, lower graphics clocks and less AI throughput, while MSI keeps the same display, battery and chassis. The SteamOS test covered here was run only on the Extreme model.

Summary: This is a premium Windows 11 handheld with a 12-Xe-core Arc B390 iGPU. At that price, owners will expect any OS they install to make full use of it.

The numbers, as reported​

TweakTown's summary of ETA Prime's results looks like this:

The report has a small inconsistency. It first calls the test a six-game run and lists The Witcher 3 as one of the six. Its results then include Doom: The Dark Ages, which isn't on that list, and give no figure for The Witcher 3. We haven't reconciled this and won't guess. Treat the table as the results that were reported, not a complete record of the test.

Some important details are also missing. The report doesn't say what TDP the device ran at, and it includes no frame-time data, battery or temperature readings, SteamOS build number, Proton version, or side-by-side Windows figures for this device. Only the Forza number is explicitly labeled an average. These are useful early numbers from one creator's session, not a lab review.

Summary: Games ran well above playable in this test. Without power limits or Windows comparisons, though, it can't tell you whether SteamOS is faster or slower than Windows on this handheld.

Problem one: SteamOS lets the CPU clocks drop​

The first problem is clock management. ETA Prime reported that SteamOS didn't handle CPU clock speeds well on the Arc G3 Extreme. To keep clocks high during games, he turned on the performance mode in SimpleDeckyTDP, a community plug-in for the Decky Loader framework.

The plug-in isn't made by Valve or Intel. Its GitHub documentation calls it a Linux TDP plug-in with AMD support and experimental Intel support that is still a work in progress. On Intel systems it offers:

• Per-game TDP profiles, with optional separate profiles for when the device is plugged in
• Power governor and Energy Performance Preference controls
• SMT control, plus CPU boost control where the hardware exposes it
• TDP polling, for devices that change TDP in the background

The documentation also says GPU controls are not available on Intel. The plug-in can adjust CPU behaviour but can't manage the B390's clocks.

Checking compatibility before you install​

The project says its Intel support was built for the intel_pstate CPU frequency scaling driver. To check whether your system uses it, the documentation suggests running this in a terminal:

cat /sys/devices/system/cpu/cpufreq/policy*/scaling_driver

If it returns intel_pstate, the project says your device should be compatible. That's a basic check, not a guarantee. You need Decky Loader installed first. The project offers both a quick-install script and a manual install method. Intel support is experimental and changing, so use the project's current instructions rather than a copy that may be months out of date.

What we don't know​

TweakTown's story page links to a Q&A widget that asks about the battery and temperature costs of performance mode but doesn't answer it. Nothing in the reporting measures those costs. Holding CPU clocks high on a handheld generally uses more power and produces more heat, but that's general knowledge. How much it affects battery life on the Claw hasn't been measured.

Summary: The fix is a community plug-in with experimental Intel support and no GPU controls. Check that your system uses intel_pstate before installing it, and expect it to cost some battery life, though nobody has measured how much.

Problem two: XeSS runs without XMX acceleration​

The second problem affects image quality. ETA Prime found that SteamOS couldn't use the XMX matrix engines built into the B390, so the XMX-accelerated version of Intel's XeSS didn't work. The DP4a version of XeSS still runs as a fallback. In his testing it performed worse and looked worse than the XMX version. That explains why FSR was used in every upscaled result in the table.

The same problem showed up earlier on Intel's desktop Arc B580, which is a different product from the B390 iGPU. VideoCardz reported from ETA Prime's B580 testing that SteamOS can now run on desktop Intel Arc graphics. Early workarounds required first installing an older repair image with a Radeon GPU, then swapping to the Intel card. VideoCardz's later coverage of SteamOS 3.9 on the Main branch says the B580 now boots directly. It also says the open-source Linux driver path doesn't expose the B580's XMX engines to XeSS, that XeSS frame generation isn't available in that setup, and that FSR frame generation still is. Those findings are from the desktop card. They're consistent with the handheld result, but they don't prove the B390 behaves exactly the same way.

Summary: Intel's best upscaler on Windows is currently its weakest on SteamOS. Plan to use FSR until the Linux driver exposes XMX.

How SteamOS support for Intel got here​

Valve has been adding Intel support to SteamOS in stages for several months:

1. SteamOS 3.8.7 beta (June). Steam Deck HQ reported that the changelog added initial firmware for upcoming Intel handhelds and fixed Bluetooth on some Intel handhelds. ETA Prime tested that build on the Lunar Lake MSI Claw 8 AI+. TweakTown said it achieved playable performance in several games all the way down to 15 watts, but also noted that Cyberpunk 2077, where the game ran worse compared to the same game running on Windows, was an exception.
2. Follow-up betas. Tech Times noted that the cumulative 3.8.8 beta, released June 9, added further MSI Claw control fixes in Desktop Mode.
3. SteamOS 3.9 on the Main branch. The Arc B580 boots without the Radeon swap trick. TweakTown says 3.9 is the version where Intel hardware finally works without workarounds.

Valve has been careful with its wording throughout. Tech Times pointed out that the company did not announce Intel Arc support, and that Mesa Xe driver immaturity keeps Intel gaming below Windows performance in its assessment. An out-of-the-box boot on the Claw 8 EX is real progress. It still doesn't mean Valve has declared full support.

Should you replace Windows 11 on your Claw?​

Here's how it looks for a Claw 8 EX owner today:

• Reasons to try SteamOS: a console-style interface, quick suspend and resume, and, based on this test, frame rates that stay comfortably above 60 FPS in demanding games at 1080p with FSR.
• Reasons to stay on Windows 11: XMX-accelerated XeSS and XeSS frame generation, MSI's own TDP tools, and no need for an experimental plug-in to keep the CPU at full speed. Windows also runs games with anti-cheat systems that block Linux, which is a long-standing gap and not specific to this test.
• Middle ground: dual-boot, or test SteamOS on a spare drive, if you want to try it without giving up Windows. That's standard practice for any experimental OS, not something from the source report.

The takeaway​

One creator's test shows the Arc G3 Extreme running current games on SteamOS at playable-to-excellent frame rates. It also shows two gaps. SteamOS doesn't manage CPU clocks well enough by itself on this chip, and XMX-accelerated XeSS doesn't work on Linux yet. Both look like software problems rather than hardware limits. The first could be fixed in Valve's power management and the second in Intel's Mesa driver work, but neither company has announced a fix.

For now, SteamOS on the Claw 8 EX is worth trying if you're comfortable installing Decky Loader and running a terminal command. It isn't yet a replacement for Windows 11 for most owners.