Key Takeaways
1. The Phawx created a custom PC to closely replicate Valve’s Steam Machine for performance testing.
2. The CPU used in the test was matched to Valve’s semi-custom AMD Zen 4 processor, with similar core and thread counts and power constraints.
3. The dedicated GPU chosen, Radeon 7600M XT, shares architecture with Valve’s expected GPU, though it has more compute units; performance is limited by bandwidth.
4. Power management techniques like AMD Smart Access Memory and SmartShift were utilized to simulate the Steam Machine’s design, highlighting the need for efficient power distribution.
5. Testing showed that achieving 4K 60 FPS gameplay is challenging, with reported frame rates often around 30-40 FPS in demanding games, despite claims of significant GPU performance improvement.
Valve’s Steam Machine is still a few months away from being launched, yet the gaming community is already trying to estimate how well it will perform. The YouTube channel The Phawx took this concept to another level by constructing a small PC that mimics Valve’s upcoming hybrid console. Rather than just using similar components, they work to closely replicate the Steam Machine’s CPU performance, GPU limitations, power constraints, and overall system design.
Testing Valve’s Claims
The purpose of this effort was to test Valve’s significant performance assertions, including the anticipated six-fold GPU improvement over the Steam Deck and the capability to achieve 4K 60 FPS with FSR. They measured how closely their custom-built system could mirror these expectations.
First, the creator matched the CPU setup of the Steam Machine. Valve’s device features a semi-custom AMD Zen 4 processor with 6 cores, 12 threads, a boost clock of up to 4.8 GHz, and a 30 W power cap. To imitate this, the creator utilized an AMD 8840U laptop CPU and turned off two of its eight cores, while also parking the related hyperthreads, resulting in exactly 6 cores and 12 threads being active.
Simulating Power Constraints
To simulate the 30 W CPU power limit from Valve, the processor is set to a maximum of about 4 GHz during workloads that use all cores. The creator’s tests show that achieving the advertised 4.8 GHz is only feasible during single-core tasks, mirroring the expected behavior of Valve’s chip.
An earlier Geekbench entry for a device tagged “Val Fremont,” which many believe to be an initial Steam Machine model, shows cache configurations similar to the 8840U. This alignment allows the creator to not only match core counts but also replicate the L1, L2, and shared L3 cache setups by parking the appropriate cores.
They also entirely disable the integrated GPU, suggesting that the Steam Machine’s custom APU will likely have its iGPU disabled.
Matching the GPU
For the dedicated GPU, they opted for a Radeon 7600M XT, which shares the same Navi 33 architecture as Valve’s GPU. The Steam Machine is expected to have 28 CUs, unlike the 7600M XT’s 32, so they limit the boost clocks to better align with the roughly 9 teraflops estimated for Valve’s hardware. The card usually operates at 2.3 GHz, in contrast to Valve’s leaked peak clock of 2.45 GHz. Both use 32 MB of Infinity Cache and roughly 288 GB/s of effective bandwidth, which they claim is more suited for 1080p and will depend heavily on FSR to achieve 4K 60 FPS targets.
They also mention that the extra compute power of the 7600M XT doesn’t provide much actual benefit since bandwidth is the main limiting factor, suggesting that Valve’s lower-CU GPU might actually offer a more balanced performance despite being weaker on paper.
Power Management Insights
To further match the Steam Machine’s design, The Phawx enabled AMD Smart Access Memory and SmartShift, which they believe Valve might also use to unify power budgets between the CPU and GPU. In their tests, a limit of 28 W causes both components to downclock significantly, leading to a noticeable drop in performance. Raising the shared TDP back to 150 W restores normal functionality.
They argue that this illustrates how much the Steam Machine might need to manage power distribution between its components within a small enclosure.
For performance testing, The Phawx concentrates on how closely their setup can achieve Valve’s claim of 4K 60 FPS gameplay with upscaling and frame generation, even if it means keeping graphics settings at their lowest. Their aim, as they clarify, is not to maximize visual quality but to determine how far they can push resolution and frame rates on hardware designed to simulate the Steam Machine.
Game Performance Analysis
They start with God of War 3 in the RPCS3 emulator, running at 720p with recommended settings and speed patches turned off. Performance stays just below a locked 60 FPS, but remains relatively playable, providing a realistic view of CPU-bound emulation performance at a 4 GHz all-core cap.
In Indiana Jones and the Great Circle, the system outputs at 4K, uses low settings, and relies on XeSS Performance mode to approach the 60 FPS target. Even with the heavy upscaling, the game typically runs closer to 30 FPS, with The Phawx pointing out that ray tracing is especially taxing for RDNA-based GPUs.
For Starfield, they again aim for a baseline of 4K 60 FPS, using 4K output, a 50% render resolution, low graphics settings, and FSR 3 without frame generation. The outcome is generally around 30–40 FPS, dropping lower in densely populated areas like Akila City.
The YouTuber also revisits Valve’s assertion of six times the GPU performance of the Steam Deck. They report that in GPU-bound tests like Returnal, their matched setup performs roughly 6.5 times faster, noting that their GPU is somewhat stronger than what is anticipated for Valve’s system, although both utilize Navi 33 silicon.
In addition, The Phawx tests other games such as God of War Ragnarok, Warhammer 40,000: Space Marine 2, and Spider-Man: Miles Morales and shares their concluding thoughts while also speculating on the Steam Machine’s possible pricing. You should definitely check out the video below for the complete analysis.
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