What's up with the lack of PlayStation 3 emulation on PS5? While Microsoft has delivered Xbox 360 emulation for both Xbox One and Series consoles, Sony has yet to deliver emulated games from "the Triple" on its latest console - but now, thanks to the recent release of Linux on PlayStation 5, we can find out why. RPCS3 is by far the most advanced PS3 emulator around (years in the making!) and it runs just fine on PS5. How well each PS3 game runs can vary dramatically though - and ultimately, it all comes down to how difficult the exotic Cell processor is to emulate. Some games are dramatically transformed for the better on PS5 via RPCS3 emulation. However, those that tap into the power of the Cell and its SPU satellite processors struggle.

Getting PS3 emulation working on PS5 is relatively easy - if you have an exploitable console. Currently, firmwares up to 6.02 are supported and it's a relatively simple matter of running the exploit and injecting a payload to boot into Linux via USB. From there, I moved my Linux install to an SSD within the PS5's m.2 bay and then installed RPCS3 as normal. It's available both on Windows and Linux, meaning that the emulator runs natively on PS5, no Proton translation layers required.

My first experiment was to replicate my first PlayStation 3 gaming experience - Ridge Racer 7 running at 1080p60 at launch. It's still a brilliant game and one locked to the PS3: there's no way to play it anywhere else outside of emulation. It's an early game that doesn't tax the Cell processor hard, so 60 frames per second is no problem. On top of that, RPCS3 can boost internal resolution, meaning I could run the game locked at 4K 60fps with very little issue. It looks great, it plays great, this is the PS3 emulation dream on PS5.

Other launch titles run well too. Resistance: Fall of Man wasn't an especially sophisticated game compared to the first-person shooters to come, but again, I can run it at 4K without problem. 30fps was a match, although RPCS3 runs this with incorrect frame-pacing - something that can likely be fixed (GameScope perhaps?) but likely wouldn't be a problem for an actual PS3 emulated properly brought to PS5. The point is that our experiments here are more about what's potentially possible, not a fully polished experience.

I then tested Heavenly Sword by Ninja Theory. This wasn't exactly a great game as such and ran terribly - in the 20s or lower with obtrusive screen-tearing. PS3 on PS5 though? I could pretty much run the game locked at 30fps at 5K resolution - 5120x2880. That's a 16x boost to initial resolution. Not every game can do this kind of graphical scaling - but there are indeed plenty of wins here for running PS3 games on PS5 with vastly cleaner visuals.

These launch games didn't particularly tax the Cell's SPUs - notoriously the most difficult emulation challenge. And it's clear that games that do use the SPUs vary in success level. I tried GTA4 and its episodes and the Rockstar epic (again, not available to PS5 users) and the game effectively ran in slow motion. We know it's a CPU emulation problem and not a graphics issue because running the game at 4K output produces pretty much identical frame-rates.

Now, better results are capable on PC - but that's because the latest generation of CPUs (especially AMD offerings) have the performance and features that the cut-back Zen 2 in the PlayStation 5 does not.

Which brings us to Metal Gear Solid 4. The good news is that a proper remaster is on the way and that's just as well because a game that could often run very poorly on PS3 runs worse on RPCS3 on PlayStation 5. Again, it's not a GPU problem: a 9x boost to resolution makes no difference. It does seem to be that emulating the SPUs here is just too challenging. While the result is often worse than PS3, there are areas where the original console and PS5 are neck-and-neck - though it's likely down to a GPU limitation on PS3 and a CPU emulation bottleneck on PS5. Fascinating stuff.

And the further you go into the PS3's life cycle, the more those SPUs were used and the less effective RPCS3 on PlayStation 5 hardware can be. God of War Ascension has basically been forgotten by Sony at this point, but is one of the most impressive tech powerhouses PS3 ever delivered, with breathtaking use of all system resources. RPCS3 on PS5 just can't get close to original hardware - even when we cut down SPU utilisation.

Back in the day, Sony introduced MLAA (morphological anti-aliasing) that used the SPUs to detect and smooth edges. We were quoted a 25ms total processing time - 5ms per SPU. That's a remarkable amount of processing time for a post-process filter, but it was widely used, especially in Sony first party games. Game patches for RPCS3 remove it, lowering the CPU burden, but the final God of War title on the Triple still proves too much for the emulator running on PS5.

The same can be said for Killzone 2, which also struggles on PS5. There are moments where it outperforms the original game running on PS3, but for the most part, it runs slower. It seems that aspects like enemy AI, animation and especially post-processing used the SPUs extensively, which makes for a poor experience on RPCS3 on PS5.

Killzone 3 is much more interesting, however. This one uses MLAA and emulating it on PS5 causes big frame-rate problems. Disable it, however, and for the most part, PS5 can hit the 30fps performance target. With the CPU limitation removed, we can then tap into the GPU and it's possible to hit a relatively stable 4K 30fps. There can be some dips when the combat zone is flooded with Helghast but even so, it's fascinating to see the 2011 Killzone offering run fine on RPCS3 on PS5 while the 2009 game does not.

Killzone 3 though. Well, this is very, very interesting. Check out this visualisation. MLAA is used in this game where it wasn't in Killzone 2, occupying a ton of SPU time. With MLAA active we can't hit 30fps here even in a relatively light scene. But turning off MLAA via game patches means we can hit 30fps, not just at 720p but 1440p and 4K too. Excuse the poor frame-pacing again but vast swathes of gameplay within Killzone 3 play out just fine at 30 frames per second, no matter how intense the environments, so in this sense, Killzone 3 is clearly better suited for emulation than Killzone 2, which is certainly a surprise.

There's also good news for the original MotorStorm trilogy, again locked to the PlayStation 3. The debut entry runs just fine on PS5 at the original's 30fps with resolution boosted from 720p to 1440p. We can do even better with the sequel - Pacific Rift - where a locked 30fps is attainable at 4K resolution. The excellent MotorStorm Apocalypse can also run pretty much locked to its target 30fps too, with the MLAA removal trick lightening enough of the SPU load to run at its intended performance level.

So, with the exception of GTA4 and Metal Gear Solid 4, I only played games that will only ever be available on PlayStation 3 and where therefore emulation is the only option. The results are clear: the Cell architecture continues to cause challenges for emulation and at this point, I can't help but feel that if Sony were to deliver an emulator for PS5, they would have done so after five and a half years. We've talked about the first PS3 emulator for PS5, but right now at least, it's pretty basic stuff. However, a developer called Implicit Conversions delivered the PS2 emulator for PS4 and PS5, and there has been talk of a PS3 emulation backburner project.

However, based on everything I'm seeing here, my best guess would be that PS3 emulation may finally become viable on the next generation consoles, where the Zen 6 CPU architecture should in theory have the horsepower and features to deliver full speed emulation of the Cell. At least the GPU side of the equation is not a problem. Every game I tested could run at much higher resolutions. Titles like Virtua Fighter 5 and Ninja Gaiden Sigma could also be run at 5K resolution in addition to Heavenly Sword - and I'm sure there are many others.

So, PS5 Linux blows open the closed console architecture and allows us a fascinating window into the Sony console's capabilities outside of the walled garden ecosystem the hardware was built for. We've done path tracing and now PS3 emulation, both offering up interesting perspectives on new ways the hardware may be utilised - and where it may find its limits.

What we've ultimately discovered is that similar to the last-gen consoles, the hardware balance of PS5 favours the GPU over the CPU and while RPCS3 is best used on a modern PC with a recent CPU architecture, it's still been fascinating to look at PS3 emulation on PS5 to confirm that Cell processor emulation really is very, very tricky.

But here's an interesting thought to end with: if Project Helix offers some way to access the Windows desktop in the same way that SteamOS offers access to standard Linux, well… there'll be nothing to stop you installing RPCS3. And it would be a remarkable situation to see full speed PS3 emulation first on a Microsoft console…