AMD 4800S Desktop Kit review: playing PC games on the Xbox Series X CPU
Jul 13, 2023
Repurposed Xbox silicon powers a fascinating China-only PC motherboard.
What if you could take the Zen 2 CPU cores found within Xbox Series X and PlayStation 5, transplant them onto a PC motherboard, install Windows and actually play PC games on them? Short of hacking the console and somehow crafting drivers for it, it's a pipedream, but we can do the next best thing. AMD recently - and somewhat stealthily - released the 4800S Desktop Kit for Chinese OEMs. It's a Micro ATX motherboard built around the Xbox Series X APU, shipping with 16GB of GDDR6 memory. The integrated GPU is disabled, but it is possible to install Windows on it, you can attach a decent graphics card - and yes, you can play PC games on an Xbox CPU.
The idea that this product even exists is baffling, but there is some logic to it. Not every PS5 or Series X chip that makes it off the production line is functional. There can be imperfections in the silicon that write off the chip - or parts of it. In this case, AMD chooses chips with defective GPUs, disables that graphics component and uses the CPU portion only. As you'll see in the accompanying video - and indeed in the headline image - we can be sure it is Series X silicon because if you put the two chips side by side, they're a match.
There's also precedent with this happening before. The AMD 4700S Desktop Kit follows the same principles, although that's built around defective PlayStation 5 processors. I do own a 4700S, but it's a bit of a dead weight. PCI Express bandwidth is too limited to support high-end graphics, there's no NVMe functionality and only two SATA ports. Meanwhile, the cooler is slight to say the least. With the 4800S, AMD resolves all of these issues. There are four SATA ports, an NVMe slot, a meatier cooler and, although GPU bandwidth is still limited, the 4x PCIe 4.0 interface does produce good results from higher-end graphics cards.
I do actually own the 4700S Desktop Kit - and others have covered it extensively. I wrote off our coverage because PS5-level gaming simply wasn't possible on it, owing to the PCI Express bandwidth limitation. We bought the 4800S on the recommendation of DF supporter, Fidler_2K, who noted its more luxurious spec. However, actually acquiring one was problematic. I bought the 4700S on eBay from an Italian supplier. While we were aware the 4800S was for sale, we found it nigh-on impossible to actually get it exported.
Thankfully, my colleague Will Judd and his wife Stella visited China a couple of months back and managed to secure one - but even then, it required liaising with a local PC shop, getting an entire prebuilt system shipped from elsewhere in China and then stripping the board out in preparation for its return trip to the UK. So, thanks to Will, Stella and indeed Fidler_2K for making this project possible.
Where to begin with 4800S Desktop Kit testing, though? Before having fun with gameplay, I thought I'd do some basic benchmarks stacking it up against the mainstream CPU we use as a matter of course in our PC gaming reviews - the now-classic Ryzen 5 3600. CineBench R20 gives us an 1184 point single thread score on the 3600, and an 1148 score on the 4800S - so the 4800S is barely outside of margin of error there in terms of the differentials, which is not surprising as both are Zen 2 processors with similar single core turbos. On multicore scores, the 4800S has more cores and therefore a higher score - 10539 vs 8113 on the 3600.
However, the biggest impact to performance is going to be in the memory system. A standard desktop CPU is paired with SDRAM modules that you choose yourself and insert into the motherboard. The 4800S desktop kit comes with GDDR6 on the board. This memory is typically used for graphics purposes, not CPU. Bandwidth is massively higher which is a good thing, but latency - the time taken for access - is also higher, which is most certainly not a good thing. On top of that, the console CPUs, and in turn the 4800S, have a lot less onboard cache than AMD's Ryzen chips. You can see how that pans out in the graphs below.
Across the whole benchmark, the 3600's much larger cache offers far higher levels of bandwidth and, as the size of the transfers increases, the 4800S can't keep pace as it runs out of cache and has to drop back to the memory modules. However, something interesting happens when the transfers break through the cache limit of the Ryzen 5 3600. Now it's the 4800S taking point, with GDDR6 memory offering nigh-on twice the level of bandwidth offered by the G.Skill 3200MT/s CL16 memory. Unfortunately, latency is problematic, as the graphs demonstrate - no matter how large the size of the transfer.
Before we go on, some words of caution in how the data should be interpreted. On a basic level, we should get some idea of the horsepower available to developers for their console titles. However, equally, we need to accept that consoles are very different beasts. The Xbox CPU is out of its natural habitat. So, just on a superficial level, the Xbox CPU and GPU are integrated into the same chip - there's no need to send out graphics commands and data over a PCI Express slot as we do on PC. On top of that, the nature of development on console and PC is very different: for Xbox Series machines, we should expect developers to tailor their CPU code to the fixed platform Microsoft has developed for them. On PC, games need to work on a plethora of different hardware.
On the flipside, this PC version of the Xbox Series X CPU has some advantages over the console set-up. With SMT active - meaning eight cores and 16 threads - the console operates the CPU at a flat 3.6GHz, with one core held in reserve for OS level functions. On the AMD 4800S Desktop Kit, the CPU acts more like a standard Zen 2 processor in that clocks are variable. Typically, it seems to run all cores at around 4.0GHz like the other Zen 2 processors we've tested. That's a circa 11 percent increase to speed, and Windows can also access all eight cores and 16 threads. There is no OS reservation here.
So, in summary, we may get a ballpark indication of the CPU horsepower available to console developers compared to other processors, but more accurately, what we're definitely getting are the results of PC versions of console games running in a Windows 11 environment. Even so, I trust you'll find the following pages quite interesting!Introduction, Synthetic Benchmarks [This Page]Benchmarks: COD BLOPS: Cold War, Crysis 3 Remastered, Ashes of the Singularity, Metro Exodus EEBenchmarks: Counter Strike: Global Offensive, Cyberpunk 2077, Flight Simulator, Far Cry 6, Hitman 3Gameplay tests at console settings on RX 7900 XTX, Conclusion