RISC-V CPU runs The Witcher 3 at 15 FPS — 64-core chip paired with Radeon RX 5500 XT GPU deliver laggy gameplay

The GOG version of Witcher 3 running on RISC-V architecture through Box64, Wine, and DXVK x86 emulation and compatibilty layers.
The GOG version of Witcher 3 running on RISC-V architecture through Box64, Wine, and DXVK x86 emulation and compatibilty layers. (Image credit: ptitSeb on YouTube)

RISC-V, the open source, royalty-free CPU architecture, is in the very early stages of development and adoption compared to mainstream ARM and x86/x64 CPUs— but despite that, Box86/Box64 developers still managed to get last-gen AAA title The Witcher 3: Wild Hunt running on a RISC-V PC. Besides Box64, which was used to emulate x86 instructions in general, Wine and DXVK helped fill the gaps using Linux instead of Windows. The developers wrote a detailed blog post on how this was accomplished and uploaded video footage of the game running on YouTube.

So, before you get too excited about a future where PC gamers don't need to rely on Microsoft, Intel, or AMD to play games, The Witcher 3 is only managing a measly 15 FPS in these conditions. However, even being launch-able, much less semi-playable on RISC-V, the game is still a significant technical achievement and bodes exceptionally well for the future of open-source architecture. A high-complexity, high-fidelity game like The Witcher 3 truly pushes the architecture to its limits. Still, it proves its capabilities simultaneously, even though a genuinely playable, immersive experience remains out of reach.

As explained by the FOSS (Free and Open Source Software) project Box86 developers in their blog post, the significant issues with running The Witcher 3 on RISC-V start with x86_x64 CPU instructions. Games and other software, in general, rely on specific CPU instructions, so when that software must be run on another hardware architecture, the new architecture needs to be able to substitute or duplicate those instructions. 

The Witcher 3 running On RiSC-V - YouTube The Witcher 3 running On RiSC-V - YouTube
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So, the major challenge of x86 emulation on RISC-V architecture is translating those x86/x64 CPU instructions into something RISC-V can actually understand. The original blog post details a few x86 instructions that are particularly tough to translate efficiently on RISC-V, which results in a lot of hardware power being spent on excessive "translation" of what used to be simple x86 instructions made complex by RISC-V architecture.

Last August, we discussed these same Box86 developers making a breakthrough by achieving fully playable 2D games on RISC-V, like Stardew Valley and World of Goo. For The Witcher 3, the developers needed to acquire a Milk-V Pioneer, a 64-core RISC-V PC with a PCIe slot. One AMD Radeon RX 5500 XT installation later, and a RISC-V PC is now capable of playing last-gen AAA titles, at least in a very limited form.

For now, this realistically isn't a big deal for anyone who wants to play games or buy a PC that can play games today. However, like the ongoing development of Windows on Arm and Proton on Linux, ongoing efforts like these show us that today's Big Tech companies won't have complete control of the PC gaming market forever. At this rate, a competent RISC-V gaming PC could be on the market within the next decade— maybe even half the time.

Christopher Harper
Contributing Writer

Christopher Harper has been a successful freelance tech writer specializing in PC hardware and gaming since 2015, and ghostwrote for various B2B clients in High School before that. Outside of work, Christopher is best known to friends and rivals as an active competitive player in various eSports (particularly fighting games and arena shooters) and a purveyor of music ranging from Jimi Hendrix to Killer Mike to the Sonic Adventure 2 soundtrack.

  • usertests
    I've played some games extensively at sub-30 on an old Llano APU.

    This video looked pretty bad, especially with the stutters. But it's a start.
    Reply
  • NinoPino
    Absolutely good for a first try on a 2Ghz 64 core CPU with DDR4 3200 and a Radeon 5500 XT in FullHD.
    Reply
  • mac_angel
    I know the CPU would be the bottleneck, but I still can't help but wonder about a beefier GPU.
    RISC came out a long time ago, and as far as I remember, it was far superior technology back then. Apple used them for a while, but at that time they were really struggling, too. I know RISC has evolved over the years, but I don't think it's evolved as much as X86 and X64 CPUs, which again, makes me wonder where they could have been now if they had have been.
    Reply
  • JamesJones44
    I wish Game devs would start to migrate to using Vulkan. Then supporting other OSs and CPU architectures becomes a lot easier. I know many have spent decades in DirectDraw and Direct3D, but I think cross platform tools are mature enough now that they really should be considered before using platform specific APIs.
    Reply
  • epobirs
    mac_angel said:
    I know the CPU would be the bottleneck, but I still can't help but wonder about a beefier GPU.
    RISC came out a long time ago, and as far as I remember, it was far superior technology back then. Apple used them for a while, but at that time they were really struggling, too. I know RISC has evolved over the years, but I don't think it's evolved as much as X86 and X64 CPUs, which again, makes me wonder where they could have been now if they had have been.
    Apple uses it now. What do you think the R in ARM stands for?
    Reply
  • usertests
    mac_angel said:
    I know the CPU would be the bottleneck, but I still can't help but wonder about a beefier GPU.
    RISC came out a long time ago, and as far as I remember, it was far superior technology back then. Apple used them for a while, but at that time they were really struggling, too. I know RISC has evolved over the years, but I don't think it's evolved as much as X86 and X64 CPUs, which again, makes me wonder where they could have been now if they had have been.
    Whatever you've heard about RISC in general a long time ago doesn't apply to some RISC-V cores running emulation today. A lot of RISC-V cores I hear about are weaker than Cortex-A55. Not sure about C920, but the clock isn't high and 64 of them aren't useful here. More importantly, the blog post explains that many RISC-V instructions were needed to implement some simple and widely used x86 instructions, leading to the low performance.

    I looked into the GPU out of curiosity and found i7-4770 and RX 5500 XT running Witcher 3 "Next Gen", which I guess is more intensive than the original game. At 1080p High, it was around 60 FPS and bottlenecked by the GPU.

    The Milk-V Pioneer has PCIe 4.0 x16, so no trouble there.
    Reply
  • Findecanor
    RISC-V is an extensible instruction set, with a small core and many extensions.
    To run 64-bit Linux, you'd need the profile RV64GC, which still lacks vector, address calculation and bit manipulation: which were ratified only in the last few years, and would be needed for instruction feature-parity with ARM and x86.

    The XuanTie T-Head 910 / 920 in the Milk-V Pioneer is a few years old and implements only RV64GC, a draft version of the Vector extension and T-Head's own proprietary extensions where many instructions can do the same as officially ratified extensions but using different opcodes.

    Box64 running on the Milk-V Pioneer that we see here does not have support for T-Head's proprietary extensions. I think the developers are prioritising official extensions.

    In other words: It is not running as fast as it will be.
    Reply
  • acadia11
    mac_angel said:
    I know the CPU would be the bottleneck, but I still can't help but wonder about a beefier GPU.
    RISC came out a long time ago, and as far as I remember, it was far superior technology back then. Apple used them for a while, but at that time they were really struggling, too. I know RISC has evolved over the years, but I don't think it's evolved as much as X86 and X64 CPUs, which again, makes me wonder where they could have been now if they had have been.
    it's not a question of superiority but approach. RISC processors haven't gone anywhere, ARM is a risc processor, the point of RISC, is it reduced complexity, simplified cpu operations , and there for reduced implementation cost but more importantly reduced power consumption. CISC processors were more common because youi think x86 CPU's became popular and all those fancy instructions you take for example AVX-512 are quite popular and lot's of software started utilizing the advanced instruction / more complex optimized sets of x86 overtime. Of course, all those operations have a transistor and implementation cost, but x86 has come a nlong way in the power department with other tricks. But RISC is certainly as evolved it's always been around.
    Reply
  • The Historical Fidelity
    epobirs said:
    Apple uses it now. What do you think the R in ARM stands for?
    The R in ARM stands for “reduced instruction set” which is a generic term for any microarchitecture that emphasizes barebones instructions (compared to x86 which is a “complex instruction set architecture”) that requires more advanced compilers to layout said instructions in a way that complex instructions are created in software. Reduced instruction set CPUs are greatly affected by the quality of the compiler used for the code being run.
    By reducing the instruction set, the micro-architectures become less intricate because they can free up transistor space that used to be occupied by complex instruction decoders, translators, and hardware that enables legacy instruction support (dating back to the 1970’s for x86 so has a quite bloated instruction set where some instructions are rarely used nowadays) to be reallocated to improve IPC and power efficiency. This is the only reason why Apple’s M-series chips are faster clock-for-clock if not held back by inferior compiling.
    Reply
  • mac_angel
    usertests said:
    Whatever you've heard about RISC in general a long time ago doesn't apply to some RISC-V cores running emulation today. A lot of RISC-V cores I hear about are weaker than Cortex-A55. Not sure about C920, but the clock isn't high and 64 of them aren't useful here. More importantly, the blog post explains that many RISC-V instructions were needed to implement some simple and widely used x86 instructions, leading to the low performance.

    I looked into the GPU out of curiosity and found i7-4770 and RX 5500 XT running Witcher 3 "Next Gen", which I guess is more intensive than the original game. At 1080p High, it was around 60 FPS and bottlenecked by the GPU.

    The Milk-V Pioneer has PCIe 4.0 x16, so no trouble there.
    I understand about the emulation and such. My point was if things were NOT bound to the x86 and x64 architecture and an emulation wasn't required. And, along with that, if RISC had have had the same rate of maturity and advancement as the x86 and x64 CPUs such as Intel and AMD.
    If RISC had have advanced as much as Intel and AMD, and PCs were more open source instead of needing those instruction sets (yes, I know they are required for the type of programming, not my point). Basically, if RISC had have been able to advance as much as Intel and AMD, and were all on an equal playing field. And, I know it was a long time ago and my memory is definitely not as great as it once was, but I do remember people saying that RISC was a superior technology back then.
    Reply