Steam Machine Windows 11 vs SteamOS Benchmarks: Nearly Equal Until VRAM Runs Out

One of the first Steam Machine Windows 11 vs SteamOS benchmarks is out, and the headline result is closer to a draw than a verdict. ETA Prime's testing across three titles shows the two operating systems within a few frames of each other, with SteamOS holding the largest single-game lead. What the benchmarks don't show is where that parity breaks down. Prior Ars Technica testing on comparable 8GB AMD hardware documented a separate, more serious problem: once a game pushes past the GPU's VRAM ceiling, SteamOS performance can fall off a cliff.

That gap doesn't appear in today's numbers. Whether it will depends on a Valve fix that hasn't been publicly confirmed as shipped.

Steam Machine Windows 11 vs SteamOS benchmarks: what ETA Prime found

These are among the first Steam Machine-specific performance figures available, covering three titles at specific settings from a single tester. That scope shapes what the data can actually support: a near-parity baseline, not a thorough verdict on which OS is better for gaming.

The largest single-game gap favored SteamOS, not Windows. SteamOS holds an 8%-plus lead in Cyberpunk 2077 at native 1080p ultra settings, while gaps across other titles stay below 3%, TechSpot reports today. The three tested titles, Shadow of the Tomb Raider, Cyberpunk 2077, and Horizon Zero Dawn Remastered, show neither OS consistently outpacing the other in gaming workloads.

The Cyberpunk result has independent support. In separate testing published yesterday, TechPowerUp found Linux ahead in the same title by 9 FPS (6%) at 1440p and 7% at 4K on high settings.

Windows does take one clear win: Geekbench 6 multi-core, where it leads by 22%, while single-core results are effectively identical, TechSpot notes. That result measures CPU scheduling and compute throughput. It says something about general system behavior; it doesn't predict frame rates in game engines that distribute workloads differently.

The current data establishes a near-parity baseline. Understanding where that baseline may crack requires looking at what happens on equivalent AMD hardware when conditions get harder.

What testing on comparable AMD hardware suggests

The Steam Machine ships with an 8GB discrete GPU, the same configuration Ars Technica used as a primary test case in its December 2025 dedicated-GPU comparison. That testing wasn't conducted on the Steam Machine itself. Ars ran Windows 11 25H2 against SteamOS 3.9 with specific AMD drivers on each platform, and the results carry the usual caveats around differing driver versions, system configurations, and SteamOS build states. Where hardware class and workloads align with the Steam Machine's, the findings are the closest methodological analog available.

Ars found that Windows generally edges out SteamOS on dedicated AMD GPUs even in scenarios where VRAM isn't the limiting factor, meaning the advantage isn't purely a memory management story. The gap varies considerably by title and workload type.

Ray tracing is where the separation becomes most consistent. In both Forza Horizon 5 and Cyberpunk 2077 with ray-tracing effects enabled on 16GB dedicated GPUs, Windows held a 15-20% performance lead over SteamOS, Ars reported. Outside ray tracing and VRAM-pressure scenarios, the gap largely collapses: Cyberpunk without ray tracing, Returnal when not hitting the 8GB memory limit, and Assassin's Creed Valhalla all came in at a statistical tie or low-single-digit differences within margin of error. In those conditions, SteamOS actually posted a small but consistent lead in average frame rates, Ars found.

For Steam Machine owners running older or well-optimized titles at moderate settings without ray tracing, today's benchmark data suggests OS choice barely registers. For ray-traced workloads or anything pressing the memory budget, Ars' December testing on comparable AMD hardware suggests Windows may hold a real advantage.

The VRAM problem: why SteamOS's real vulnerability isn't in the current tests

The Steam Machine's 8GB video memory allocation is the single most important piece of context for any OS comparison on this hardware. The current benchmarks don't expose it. Prior SteamOS testing on 8GB GPUs shows what happens when they do.

Returnal on an 8GB RX 7600 ran 60-70% faster under Windows than SteamOS. The same game on a 16GB card was essentially a tie. Ars framed the result as a SteamOS memory-management issue rather than a general GPU limitation, since the 16GB variant largely tied Windows across the same workloads, Ars reported in December 2025.

Valve engineer Pierre-Loup Griffais explained the mechanism directly to Ars: "The typical symptom that we'd expect is that once you run out of VRAM, subsequent allocations from the game will spill over to system memory, at which point a drastic performance drop would be observed since the game would partially be rendering to/from system memory across the PCIe bus," Griffais told Ars.

Griffais also said VRAM management improvements were "about to get merged into SteamOS main" at the time of that report. Whether those fixes are included in the SteamOS build running ETA Prime's current Steam Machine tests is not confirmed by any available evidence. The tests don't specify the build version, so that question stays open.

The structural context matters. The Steam Machine is Valve's first officially supported hardware with a fixed discrete VRAM allocation, as Ars noted in December. Every previous SteamOS target, including the Steam Deck, used unified memory shared between CPU and GPU. The platform never had to manage hard VRAM limits under pressure before, and the December testing suggested SteamOS still had unresolved issues with that constraint.

The current Steam Machine benchmarks likely show parity because the tested titles, at those settings, don't exhaust 8GB. That's a plausible result for older titles at 1080p. For newer open-world games at higher resolutions with memory-heavy settings, the Ars data suggests the picture may look different.

Who should stick with SteamOS, and who should consider Windows

For players primarily running older AAA titles, esports games, or anything at moderate resolution without ray tracing, today's Steam Machine benchmarks support staying with SteamOS. Performance differences are negligible, SteamOS is the purpose-built default, and in Cyberpunk at least, it's the faster option, TechSpot reports.

For games using ray tracing or newer open-world titles likely to pressure 8GB VRAM, Ars' December testing on comparable AMD hardware suggests Windows may hold a real, measurable advantage: 15-20% in ray-traced scenarios, and potentially far more when memory limits are crossed. That gap has been measured on the same GPU class the Steam Machine uses.

The practical decision hinges on a fix Valve hasn't publicly confirmed as shipped. If the VRAM management improvements Griffais described have landed in the SteamOS version ETA Prime tested, today's near-parity may hold even as game demands increase. If the fix is still pending, the tied result understates the risk for memory-constrained workloads, Ars reported.

The next round of Steam Machine benchmarks worth paying attention to won't be average-FPS comparisons in well-optimized titles. They'll be VRAM-pressure tests: newer open-world games, higher resolutions, memory-heavy settings, with explicit confirmation of which SteamOS build is running. Those results will determine whether Valve solved the problem the Steam Deck's unified memory never had to face.