Digital Foundry Article Technical Discussion [2020]

[Jawed]

Fucking hell, a 15% performance penalty for "only" having 4GB of vram instead of 8GB, when running LOW settings at 1080p. I mean, that's terrible.

GTX 680 does show a significant penalty (2/4GB) as does RX 460 (2/4GB).

Need to be careful with respect to 1% lows. The fps ratio comparing average and 1% low could be a clue in some cases.

5500XT with 4/8GB options does not show the same penalty. But it might be CPU-limited though...

In the end, "LOW" in Doom Eternal may be "too high" for most of these cards. Also, I suspect the game has been patched since this video was made, since it was soon after Doom Eternal was released (20/3/2020, video dated 27/3/2020).

This seems to be the final patch (27/5/2020) that talks about VRAM allocation:

https://store.steampowered.com/newshub/app/782330/view/2187006557874536446

but I don't know what kind of VRAM allocation is required at LOW settings.

 

[iroboto]

Flushing data in and out of VRAM should make up for any deficits in the 16GB I would have thought.

It only reduces the amount of the space needed to buffer textures. Faster the streaming the less buffering. But the speed of the drive itself is insufficient to render directly from. So the limit on the top end is determined ultimately by, how little space you need to store textures and how much vram is available, ie the total capacity.

SSDs cannot make up for total capacity deficiency. It’s a bit unfortunate they only shipped with 16GB. More would have been nice

 

[chris1515]

It only reduces the amount of the space needed to buffer textures. Faster the streaming the less buffering. But the speed of the drive itself is insufficient to render directly from. So the limit on the top end is determined ultimately by, how little space you need to store textures and how much vram is available, ie the total capacity.

SSDs cannot make up for total capacity deficiency. It’s a bit unfortunate they only shipped with 16GB. More would have been nice

You will never need with a good virtual texturing system need so much RAM, you can reach 1 texel per pixel on PS5 and XSX/XSS . I don't think geometry will be limited by RAM size too but I think if we reach some limit it will be using dynamic datastructure like BVH.

 

[Deleted member 86764]

It only reduces the amount of the space needed to buffer textures. Faster the streaming the less buffering. But the speed of the drive itself is insufficient to render directly from. So the limit on the top end is determined ultimately by, how little space you need to store textures and how much vram is available, ie the total capacity.

SSDs cannot make up for total capacity deficiency. It’s a bit unfortunate they only shipped with 16GB. More would have been nice

It should be able to do geometry too? Even HDDs have done that in open world games in the past. I would imagine that the physics engine and other core elements running the game would need to remain static anyway.

But yeah, I guess textures make up a significant majority of RAM usage.

The potential detail in a scene shouldn't be as limited as it was before. I always think back to DF's COD Warzone video, the engine is constantly flushing data in and out of RAM within a radius of the player. That potential detail would now be massive and could be much greater than something with twice the VRAM.

 

[iroboto]

You will never need with a good virtual texturing system need so much RAM, you can reach 1 texel per pixel on PS5 and XSX/XSS . I don't think geometry will be limited by RAM size too but I think if we reach some limit it will be using dynamic datastructure like BVH.

At the end points of that discussion you'll see the limits. VRAM and bandwidth are sort of what keeps the consoles kicking around for a long period of time. The more VRAM and the more bandwidth the more than can make up for the deficit in real-time compute power, in exchange for pre-computed assets, much like we saw with this generation. I would say what you saw with UE5 is only the beginning of this generation, 2021 aspirational stuff. Where games will be in 7 years time is the end point I'm looking at.

The potential detail in a scene shouldn't be as limited as it was before.

I do use the words textures, but you're right to include geometry, or shadow maps etc. All pre-baked assets.

One of the ways I like to look at things is to just remove the streaming portion out of the discussion. What you can render and see on the screen is going then be limited to what's in VRAM. Since you're not moving there is no strreaming lets say. So you would agree that if 1 system has say 2 GB of memory vs another with 16GB of memory. And you tailored the visuals to meet their VRAM sizes, you'd expect the 16GB VRAM to look much better. I guess in this example, as you have proven the PS4 over the 7870 etc, regardless of whatever it does, it just cannot run higher settings than PS4 because of that lack of memory. I'd bet if you found a stronger card with less VRAM in the same fashion would still produce inferior visuals to the PS4 for the same reason (using Death Stranding or HZD), these titles were designed with 6GB of VRAM in mind.

And so when we consider that concept, 32 would be better than 16 and so forth. The streaming element determines the rate of change we can handle in the game with respect to the size and quality of the assets. There are going to be bandwidth and compute limits so it's not like you can toss 64GB of memory on a shit video card and get great visuals. You still need the bandwidth and compute to render all those assets in the detail they deserve.

 

[chris1515]

At the end points of that discussion you'll see the limits. VRAM and bandwidth are sort of what keeps the consoles kicking around for a long period of time. The more VRAM and the more bandwidth the more than can make up for the deficit in real-time compute power, in exchange for pre-computed assets, much like we saw with this generation. I would say what you saw with UE5 is only the beginning of this generation, 2021 aspirational stuff. Where games will be in 7 years time is the end point I'm looking at.


I do use the words textures, but you're right to include geometry, or shadow maps etc. All pre-baked assets.

One of the ways I like to look at things is to just remove the streaming portion out of the discussion. What you can render and see on the screen is going then be limited to what's in VRAM. Since you're not moving there is no strreaming lets say. So you would agree that if 1 system has say 2 GB of memory vs another with 16GB of memory. And you tailored the visuals to meet their VRAM sizes, you'd expect the 16GB VRAM to look much better. I guess in this example, as you have proven the PS4 over the 7870 etc, regardless of whatever it does, it just cannot run higher settings than PS4 because of that lack of memory. I'd bet if you found a stronger card with less VRAM in the same fashion would still produce inferior visuals to the PS4 for the same reason (using Death Stranding or HZD), these titles were designed with 6GB of VRAM in mind.

And so when we consider that concept, 32 would be better than 16 and so forth. The streaming element determines the rate of change we can handle in the game with respect to the size and quality of the assets. There are going to be bandwidth and compute limits so it's not like you can toss 64GB of memory on a shit video card and get great visuals. You still need the bandwidth and compute to render all those assets in the detail they deserve.

Epic devs said the demo is not representative of the assets we will have in game because of the assets size on the SSD. The UE 5 is only a demo because of this. they target 60 fps for the demo on PS5 if it works the limit will be the asset size on SSD.

The assets are composed of 8k texture, 16k shadow maps texture, billions of polygones for assets.

 

[PSman1700]

I dont think any base PS4 or one s game is actually using 6gb purely for vram. Its way below that. But indeed, vram quantity seems the main problem for lets say a 7870, or even a 670 for that matter.
And then again, like DF talked about in their livestream, current base consoles from 2013 dont cope all that well in modern games, aside from sony first party games which still perform very well on the base ps4.
Its the multiplat games that suffer, not only on 2012 pc's, but also on the 2013 consoles. Its bound to happen at the end of every generation.
Ive tested about any popular game with the i7 920/7950 combo, and for the most, it competes favorably vs the base PS4. Sometimes trade blowing. Im also aware that that system is multiple times more powerfull, obviously optimization plays a role, in special the drivers side of things. Would say that that system performs better at equal settings, even in planetside 2.

For coming gen, its probably wise to avoid 8gb GPUs, 10GB vram seems to be the least (XSX), but id get a 16GB Ampere or Navi2, you guaranteed can tag along the whole gen that way.
PS4 and One s had very large memory sizes for their time, larger then 2012/3 mid range pc's. They had an advantage there. Now, ram increases seem to have stagnated alot.

 

[iroboto]

Epic devs said the demo is not representative of the assets we will have in game because of the assets size on the SSD. The UE 5 is only a demo because of this. they target 60 fps for the demo on PS5 if it works the limit will be the asset size on SSD.

The assets are composed of 8k texture, 16k shadow maps texture, billions of polygones for assets.

Just keep putting more on the screen. Different statues, not the same ones, different NPCs, different, all sorts of debris etc all in the air. UE5 was impressive, but it's not nearly as diverse as it should have been. The beetles were all the same, the statues with all the polygons were all the same. When you want more diversity to be in a single frame, you'll need to increase the amount of space used by textures. The higher the resolution you are running, the more effects you have going on, etc etc the more VRAM you need etc etc.

I'm not saying the systems aren't well thought out or well designed. Just looking at the desire for there to always be more of it.

 

[chris1515]

Just keep putting more on the screen. Different statues, not the same ones, different NPCs, different, all sorts of debris etc all in the air. UE5 was impressive, but it's not nearly as diverse as it should have been. The beetles were all the same, the statues with all the polygons were all the same. When you want more diversity to be in a single frame, you'll need to increase the amount of space used by textures. The higher the resolution you are running, the more VRAM you need etc etc.

They can go more diverse, this is not the problem but the assets will never be the same quality because the demo was only 10 minutes but tooks tenth of GB.The best texture will probably be 4k and not 8k*, shadows maps quality will be reduced and geometry assets will have improved polycount and better normal maps compared to current gen but they will not store Zbrush assets on the disk for use it directly in UE 5.

I think 16 GB with the SSD is ok for this gen. Devs will find 100 to 200 Gb size for a game with patch to be one of the big limit this gen.

* Texture quality was as good as what they used in the Mandalorian if I remember well what Epic said.

EDIT: Nanite virtualize geometry too and reduce the needs to have the full assets in memory and it is probably not compatible with raytracing, it means the important things is the storage speed and PS5 and XSX are well equiped.

 

[iroboto]

They can go more diverse, this is not the problem but the assets will never be the same quality because the demo was only 10 minutes but tooks tenth of GB.The best texture will probably be 4k and not 8k, shadows maps quality will be reduced and geometry assets will have improved polycount and better normal maps compared to current gen but they will not store Zbrush assets on the disk for use it directly in UE 5.

I think 16 GB with the SSD is ok for this gen.

Well you're certainly right that there's no value in complaining about it. They did their best and this is likely the most cost effective solution when you look at all the available options there are. I think having a little bit more would have actually edged one console over the other. Right now they're going to be running everything the same except for things like resolution.

 

[Jay]

More memory, bandwidth, gpu & cpu performance, faster ssd.

Can always want more, the question is, is what you got enough and a good balance for what it is targeted for.

Is the budgets both money, silcon etc well spent, if not where would you make changes.
As i don't think either console has enough fat that you could do one thing without cutting back another.

I think having a little bit more would have actually edged one console over the other.

How much is a little bit more?
As i personally don't think it would make much difference at all in actual use.

 

[iroboto]

How much is a little bit more?
As i personally don't think it would make much difference at all in actual use.

20GB vs 16GB would be just enough I think.
But thinking out loud, I suspect their devkits scale much higher.

 

[Jay]

20GB vs 16GB would be just enough I think.
But thinking out loud, I suspect their devkits scale much higher.

Additional 4GB of GDDR6?
What would you cut to make that a reality?
That's a lot in cost, heat, power.
Or would you just charge more, if so would that still be a good decision?

 

[iroboto]

Additional 4GB of GDDR6?
What would you cut to make that a reality?
That's a lot in cost, heat, power.
Or would you just charge more, if so would that still be a good decision?

No, I think what we have is enough lol. But 4GB overrides the OS allocation and provides some.

So if we look at traditional 4K cards, they are ranging about 10 gb in VRAM. You've added about 6-8GB on top of that to grow as the generation matures into mainly 4K resolution.
Right now there's only about 4 GB to grow in 7 years. Or to put it plainly, each year they can only increase the asset level over the current year by an additional 600MB yoy.
With 20GB, they can increase the asset quality yoy by 1GB per year.

After enough years it would add up to major differences I think that people would be able to see it and appreciate it.

That's probably the wrong way to look at it but it's also one that is straight forward idea of developers improving their game year over year

 

[Deleted member 86764]

Shouldn't we be including time in the equation though? Available memory over time, the SSDs allow for more effective RAM.

If one console has a HDD and 20GB VRAM and another has an SSD and 16GB, the latter console will have significantly more effective RAM over the period of a minute.

 

[iroboto]

Shouldn't we be including time in the equation though? Available memory over time, the SSDs allow for more effective RAM.

If one console has a HDD and 20GB VRAM and another has an SSD and 16GB, the latter console will have significantly more effective RAM over the period of a minute.

I would consider the SSD as the more important thing to solve, and it's the furthest behind everything else.
But at the same time, the streaming rate is a different but related bottleneck.
If you don't have enough streaming speed to replace the contents of memory faster than you can render it, you'll hit stuttering while it waits for the data. This is the streaming bottleneck.
If you render a frame and the total memory required exceeds your memory capacity, you'll also hit stuttering. This is the VRAM limit.

Streaming plays a big part in the role of managing VRAM. But it can't eliminate the VRAM limit. I guess the question I'm posing is, in 7 years time, as company tries to 1 up each other in the graphics department YoY, we will eventually hit the vram limit.

 

[PSman1700]

Intresting discussion, certainly something for DF to explore down the line i think.

 

[pjbliverpool]

Maybe DF/Alex can do a DF Retro article on this, its rather time consuming but when they have time Its already tiring for me testing and comparing between 7950 and 670/PS4.

Yeah "GPU's, a generation later". It'd be a really interesting article.

I guess you mean Series S?

The new consoles are even more like a PC in some respects now, their SSDs (when using compression) allow for transfer speeds within the bandwidth range of old RAM (like DDR3). It's really not that far from being a second (and gigantic) pool of RAM.

The latency is about 2 orders of magnitude different though if I recall correctly.

Microsoft estimate the memory to be equivalent to have 2.5 more RAM without a SSD. There is 13.5 GB available to the game comparable to 33.75 GB of unified RAM.

This is similar to what I described above in terms of how system RAM could be used to reduce VRAM requirements. Having a pool of memory, be it RAM or SSD that allows for very fast swapping in and out of VRAM will reduce the overall size requirement for the VRAM.

I think the consoles will run better at end of generation than base PS4/XB1 because of the 16GB unified memory couple with SSD

Do you mean run better in relative terms compared to PC's of the day? If so I agree on the CPU, and possibly the GPU, but not so sure of the above. PC GPU's are in a far better place at the start of this generation in terms of VRAM than they were at the start of last generation. When these consoles hit the market there will already be GPU's available with 100%-150% of their total available memory while even mainstream GPU's will be sporting 50%. At the start of the last generation the highest end had only 25%-75% of available console memory while mainstream was more like 12.5%.

I don't see the SSD changing that as by the end of this generation, SSD's and Direct Storage with some form of non-CPU based decompression like RTX-IO are likely to be mainstream in all serious gaming PC's so the playing field is already equalised in that regard. In fact if anything mainstream gaming PC's by then could have a pretty sizeable IO advantage, at least in relation to the XSX, and since games will likely be built on the premise of saving as much VRAM as possible by leaning on IO performance, that may act as a multiplier of VRAM size in favour of PC GPU's. And that's before considering the additional potential system RAM adds that I mentioned above.

 

[Deleted member 86764]

Yeah, agreed. Although the consoles are proportionally more powerful this time, they don't have the significant RAM advantage.

Only wild card is the SSDs, but I think the PC will overtake quickly

 

[Shortbread]