It is now the end of March 2020. A lot has happened this month, and we now have the full specs of the next generation home consoles from both Microsoft and Sony. The “too long, didn’t read” of it is that Microsoft engineered a box that is pure brute force and outperforms Sony’s machine on multiple fronts, a reverse from the previous generation. Sony, however, opted for efficiency and speed. Their GPU is clocked higher and their SSD rates at 5.5GB/s of raw uncompressed data compared to Microsoft’s 2.4GB/s. Since the PlayStation 5's tech talk, the SSD has been touted as Sony’s trump card, the hardware that will win them the war. Devs have sworn up and down that the SSD makes all the difference, fans have hung on Sony’s every word that this SSD is absolute perfection, but is that the actual truth?
On the surface, you could argue that it is indeed true. After all there is a 3.1GB/s difference in raw speed, and a 3.2-4.2GB/s difference in compressed speed. That’s a significant different and as a result the theoretical performance of the PlayStation 5's Solid State Drive gives it a huge advantage over the Xbox Series X’s drive. However, that is surface level performance. That is what manufacturers expect the components to run at if everything is running smoothly, with or without their individual feature sets that enhance the capabilities of their drives.
That brings me to my first point and the one I’ve found most frustrating when discussion of the consoles SSD’s comes up. When Mark Cerny unveiled the technical details of the PlayStation 5 he spent a lot of time talking about the Solid State Drive and really diving in to how they solved so many problems plaguing your average SSD and what they did to bring every little ounce of performance to the table for developers to use, to maximize the potential of their SSD. They had a whole set of features, named or otherwise, that made this all possible. Shortly afterwards people began claiming that Xbox Series X has no such features, that Microsoft just slapped an SSD into the machine and called it a day. That is, however, far from the truth and I want to dispel such notions. And it’s name is...
The Xbox Velocity Architecture was announced at the same time as the rest of its technical specifications. However, it and its associated features were overlooked. Why? Based on the reaction to Sony’s presentation, it likely came down to the fact that the XVA doesn’t really come with concrete numbers, it doesn’t come with the specs that people wanted to see and compare. People wanted the TFLOPs, they wanted the CPU numbers and the GPU numbers, they wanted the RAM count and speed, and they wanted the size and speed of the SSD. They didn’t care about the under the hood tweaks that make what you see on the surface better. Here are the four relevant bullet points to XVA as listed in the Xbox Series X Glossary:
- Xbox Velocity Architecture – The Xbox Velocity Architecture is the new architecture we’ve created for the Xbox Series X to unlock new capabilities never-before seen in console development. It consists of four components: our custom NVMe SSD, a dedicated hardware decompression block, the all new DirectStorage API, and Sampler Feedback Streaming (SFS). This combination of custom hardware and deep software integration allows developers to radically improve asset streaming and effectively multiply available memory. It will enable richer and more dynamic living worlds unlike anything ever seen before. It also effectively eliminates loading times, and makes fast travel systems just that: fast.
- DirectStorage– DirectStorage is an all new I/O system designed specifically for gaming to unleash the full performance of the SSD and hardware decompression. It is one of the components that comprise the Xbox Velocity Architecture. Modern games perform asset streaming in the background to continuously load the next parts of the world while you play, and DirectStorage can reduce the CPU overhead for these I/O operations from multiple cores to taking just a small fraction of a single core; thereby freeing considerable CPU power for the game to spend on areas like better physics or more NPCs in a scene. This newest member of the DirectX family is being introduced with Xbox Series X and we plan to bring it to Windows as well.
- Hardware Decompression – Hardware decompression is a dedicated hardware component introduced with Xbox Series X to allow games to consume as little space as possible on the SSD while eliminating all CPU overhead typically associated with run-time decompression. It reduces the software overhead of decompression when operating at full SSD performance from more than three CPU cores to zero – thereby freeing considerable CPU power for the game to spend on areas like better gameplay and improved framerates. Hardware decompression is one of the components of the Xbox Velocity Architecture.
- SamplerFeedback Streaming (SFS) – A component of the Xbox Velocity Architecture, SFS is a feature of the Xbox Series X hardware that allows games to load into memory, with fine granularity, only the portions of textures that the GPU needs for a scene, as it needs it. This enables far better memory utilization for textures, which is important given that every 4K texture consumes 8MB of memory. Because it avoids the wastage of loading into memory the portions of textures that are never needed, it is an effective 2x or 3x (or higher) multiplier on both amount of physical memory and SSD performance
So as you can see, Microsoft has covered every base that Sony has. To give Sony’s side of the story, which is not so concisely laid out, I looked to the Digital Foundry interview with Mark Cerny that released alongside Sony’s “Road to PS5" presentation for the information I needed. Here is what was said:
“The controller itself hooks up to the main processor via a four-lane PCI Express 4.0 interconnect, and contains a number of bespoke hardware blocks designed to eliminate SSD bottlenecks. The system has six priority levels, meaning that developers can literally prioritise the delivery of data according to the game’s needs.
The controller supports hardware decompression for the industry-standard ZLIB, but also the new Kraken format from RAD Game Tools, which offers an additional 10 per cent of compression efficiency. The bottom line? 5.5GBs of bandwidth translates into an effective eight or nine gigabytes per second fed into the system. “By the way, in terms of performance, that custom decompressor equates to nine of our Zen 2 cores, that’s what it would take to decompress the Kraken stream with a conventional CPU,” Cerny reveals.
A dedicated DMA controller (equivalent to one or two Zen 2 cores in performance terms) directs data to where it needs to be, while two dedicated, custom processors handle I/O and memory mapping. On top of that, coherency engines operate as housekeepers of sorts.”
So as you can hopefully see, Microsoft and Sony are covering the same bases, recognizing the same problems that come with Solid State Drives, and trying to maximize their potential. A question you may ask then is “Well if Sony could do it, why didn’t Microsoft also go for a super fast SSD to match the rest of their high end components?” And there are likely multiple answers to that question. Cost is probably a big one. SSD’s of speed comparable to that of the PlayStation 5 aren’t even on the market yet and won’t be until later this year, and one such SSD that has been revealed is priced at US$300+. That’s not cheap. Microsoft’s proprietary SSD memory cards are likely to be cheaper than that which would also speak to how cheap the internal drive is. However, a second and more than likely major contributor to its speed, is heat generation and cooling.
If you’re at all familiar with the Xbox 360, you’ll know that it suffered severely from overheating problems. These problems were indicated by what became known as the Red Ring of Death. Microsoft spent a lot of effort on the next generation Xbox One to eliminate this issue, and yet again with the Xbox One X and its vapor chamber cooling. PlayStation 3 suffered from a similar issue which became known as the Yellow Light of Death. If you got the Red Ring or the Yellow Light, it was off to be repaired for your machine. My Xbox 360 Pro didn’t get the Red Ring of Death, but it did suffer another heat related error which was ironically temporarily solved by purposefully overheating the console for a few hours. Eventually though it stopped working altogether and had to be sent in for repairs.
I digress, the point is that Microsoft is VERY concerned about just how much heat they’re generating and just exactly how they can solve it. You can laugh all day about the fact that the Xbox Series X looks like a mini-fridge, but make no mistake it’s gonna run quiet, and it’s gonna run cold. From the powerful fan and vertical intake(Or horizontal if you’re so inclined. It’s all just in one end and out the other.)...
To the vapor chamber...
To the heat-sink built right into the chassis...
And finally to the split-motherboard design...
The entire console is engineered from top to bottom, stem to stern to keep everything as cool as humanly possible. And in case you weren’t aware, while SSD’s do not have moving parts they can still get pretty hot and if they get too hot performance will begin throttling, not to mention the heat can actually permanently degrade and damage the SSD. Microsoft wants their SSD to maintain consistent performance under ANY circumstance and this even extends to their proprietary memory card which has been engineered not only to dissipate its own heat, but also for the consoles cooling capabilities to extend to that plug and play device to keep it cooled off and performing exactly the same as the internal drive.
Microsoft has perfected the art of cooling home consoles and maintaining consistent performance. Sony, however, still hasn’t proven that they can do the same. The PlayStation 4 and the PlayStation 4 Pro are both jet engines, running extremely hot to the point their cooling solutions can’t keep up and they can act like heaters for your room in the winter. And if the actual, literal heat wasn’t enough to convince you, I have personally found that whatever game I’m playing begins to suffer performance problems that didn’t exist earlier in the play session, a side effect of the hard drive and other components getting hot.
Where am I going with this? Well, Sony doesn’t have the greatest track record of cooling their consoles, even the PlayStation 2 could get hot to the touch. It’s one area they’ve never been particularly good at and there is the potential for that to continue with the PlayStation 5. We’ve all seen the leaked dev kits:
Notice just how many holes there are for the airflow. It’s generating a lot of heat and they’re trying to expel it from as many places as possible, but with such a compact form factor, they don’t have the room for a large powerful fan like in the Xbox Series X. Whether they’re using vapor chamber cooling is also up for debate, but that’s only part of a larger equation. A 5.5GB/s NVMe SSD is going to get HOT, and that’s to say nothing of the GPU and CPU as well as other components inside the system which also generate additional heat. And as I already mentioned, heat is bad for the GPU and CPU, it’s decidedly worse for the SSD. If Sony cannot adequately cool their prized SSD, it will throttle hard. They’ve already straight up said it can actually run too fast that it needs to be purposefully throttled unrelated to heat. So if you have that required throttling, thrown on top of heat throttling, and the heat slowly killing the drive itself and degrading its performance, Sony’s ace begins to turn into a joker. And then we have the external SSD’s. You can only use the ones that Sony themselves approve as it needs to be able to fit into the slot and match the performance of the PlayStation 5. However, unlike the Series X’s proprietary cards, third party off-the-shelf SSD’s may or may not have heatsinks, and whatever cooling the PS5 can provide may not be adequate enough to keep them sufficiently cooled.
At the end of the day if Sony can keep their SSD cooled off to the point where it never degrades and it doesn’t need to be throttled(at least due to heat.), they can likely maintain a performance advantage over Microsoft’s Xbox Series X. However that also brings us back around to a previous point in that Microsoft’s performance is consistent, and not only consistent, but also extremely efficient thanks to their Velocity Architecture. Possibly even more efficient than Sony’s feature set if only to a certain degree.
So to bring this long-winded article to a long-winded finale, I’d like to share a quote from Digital Foundry along with some tweets that further explain just how Microsoft’s SSD operates:
“Our second component is a high-speed hardware decompression block that can deliver over 6GB/s,” reveals Andrew Goossen. “This is a dedicated silicon block that offloads decompression work from the CPU and is matched to the SSD so that decompression is never a bottleneck. The decompression hardware supports Zlib for general data and a new compression [system] called BCPack that is tailored to the GPU textures that typically comprise the vast majority of a game’s package size.”
(Side note: Note how they say that the high speed decompression block can deliver over 6GB/s, and then recall how the official specs say that the compressed speed is 4.8GB/s. Microsoft’s decompression block is capable of going higher than the listed spec, the listed spec is more than likely just the safe spec and going higher may or may not run hotter than the cooling can handle. To elaborate for those that might not quite understand, the SSD can push around 2.4GB/s of uncompressed data. To get more, that data is compressed and speeds reach up to 4.8GB/s where it is then decompressed by the decompression block. In other words, base speed versus true speed and it’s all thanks to the way compression and decompression happen. 2.4GB/s doesn’t mean as much as it might seem to on the surface.)
Ok, so my guestimation for how fast SeX could stream in data from the SSD was WAY off. Actual numbers were MUCH higher than I estimated.
Rather than 40-50MB/frame @ 60fps, it’s ~100MB/frame @ 60fps
Engines will be architected to account for this new info pic.twitter.com/1phG3yCHG6
— Louise Kirby (@Kirby0Louise) March 16, 2020
Some back of the envelope figures:
- Kraken: Reduces the size of a complex non-RDO encoded BC7 format texture (say a normal map) by approx. 20-30%.
- BCPack: Approx. 50+% size reduction. Depends on how far MS pushed the tech. Definitely more effective than just Kraken alone.
— richgel999 (@richgel999) March 22, 2020
We’re still waiting on MS to reveal more BCPack details. But I strongly suspect that they are directly compressing the BCx texture bits, like the crunch library used in Unity. Custom compressors (if properly made) are stronger than generic lossless solutions like Deflate/Kraken.
— richgel999 (@richgel999) March 20, 2020
So just out of the box - assuming Sony doesn’t ship really well optimized RDO encoders for texture data - Microsoft’s solution may very well be able to deliver more usable texels per second into RAM from disk than Sony’s.
— richgel999 (@richgel999) March 20, 2020
And lastly, a developer going by the username JR78 left a comment on a Verge article that also provides valuable insight, and here is the quote(It’s long, sorry, but this article is already long so might as well just throw it all in here.):
“We also don’t know how well cooled the SSD is on the PS5. MS explained their cooling and how their SSD solution can basically run a constant storage bandwidth.
The key on the XSX is that MS touts the numbers, from storage to teraflops to memory bandwidth to clocks, are all constant and predictable. There is no overlock or underlock. You know what speed your storage will go at, what speed your CPU and CPU cores will go out, how fast your memory will be, etc. This makes optimizing much easier because they have made performance sustained and predictable.
So we are basically getting a PCIe 4.0 SSD on the PS5. With that comes more heat – that is the cost of the speed. Is there a heat sync? Does it latch into the cooling system overall? Do your add on SSDs need a heat sync or performance will suffer? Do they need a specific heat sink?
It seems that Microsoft engineering came to the conclusion that a PC m.2 drive may not be optimal for predictable sustained performance. They also may have concluded the PCIe 4.0 will run too hot. m.2 SSDs in high performance laptops and desktops cannot sustain transfer due to heat without some massive mod. If MS has figured out how to deliver a high speed storage system with excellent heat transfer, we may find in real life that the PS5 speed is not impressive.
It’s quite possible that without the proper cooling, the PS5 system may have to throttle down to slower speeds to keep cooler in regards to SSD.
The question that needs to be answered is did Sony do this to get super high speed storage that is way ahead – or did they do it so they could just get storage to match what the we will see in the XSX because they did not or could not engineer a solution for cooling?
The RAM that matters in the Xbox is far superior and will allow for faster throughput and less wasted cycles. It will be easy to allocate to specific memory addresses associated with the higher speed memory. The PS5 I/O advantage may not be much if the cooling is not adequate and MS is correct and they have adequately cooled it so the I/O can be sustained and not diminish.
Sony is not that great at cooling. I’ve heard from devs that Sony is not showing off the PS5 because it has thermal problems. Microsoft has no problem letting DF do a vid and showing them around while Sony has to rush a presentation to counter. I know from devs that have the kits that they feel the Xbox is easier to optimize and they feel games will look and feel much better on the Xbox upon release because it will take time to optimize for PS5 and figure it out.
I’ve been told it is not as bad as what happened with the PS3, but somewhat similar. The Xbox 360 was much more straightforward while the architecture for the PS3 was not. This is not the Cell, but it will require a lot of work in regards to clocks, etc to figure out how to optimize. They will eventually, but the first year may have some rougher titles that look noticeably worse than the XSX.
The one advantage the PS5 has, the I/O, may not be one if they can’t cool the drive. And the question of expansion is a real one. Do you need a heat sink on your approved SSD? The Xbox solution may be more expensive, but it also may be more consistent and easier to deal with since you don’t have to crack open the case. MS could also bulk order them up front to reduce initial cost.
I will say, MS’ way is pretty cool and reminiscent of bringing a Switch card or an old Gamecube save card and plugging it into a friend’s system. Microsoft’s setup let’s you easily bring your digital game with you, pre-downloaded, to play on other people’s XSX consoles once you login to your account. PS5 can’t do that – not with the newest games. Their external storage is not fast enough while Xbox’s is.”
In the end, the truth of the SSD matter is that Sony’s big advantage may not be so big after all, and Microsoft has certainly not neglected their SSD as many seem to believe. Only time will tell just how things turn out. Thank you for reading this ridiculously long article, possibly the longest I’ve ever written, and I hope you’ve learned more than you knew before. I sure did.
(Disclaimer: While it may seem like I’m deliberately trying to tear Sony down and prop Microsoft up, that is not my intention with this article. I fully intend to purchase a PlayStation 5 at launch if possible, while I will not be purchasing an Xbox Series X due to my plans to build a PC that outperforms it. My intent with this article was to dispel misinformation about the Xbox Series X’s hardware and show that it’s far more capable than people gave it credit for, as well as the fact that Sony’s PlayStation 5, and their SSD in particular, may have more faults than many believed.)