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Microsoft claims 200GB/s of bandwidth, gets caught fudging numbers
- Thread starter Zombie James
- Start date
bigbaldwolf86
Banned
This is why I love NeoGAF. Poking holes in the BS that is spewed out by companies and helping people understand that normally wouldn't. Thanks OP and other contributors
Moral Panic
Member
I find it interesting that in the past week or so maths have changed such that 102 + 68 = 182 now instead of 170.
Yea, that sticks out to me now that I look at it lol. Maybe I did make a mistake haha.
In any case the reasoning is there, if Microsoft's system can correctly know which items to have in ESRAM then the performance hit won't be too too bad.
Unified 176GB/s is still obviously better of course
Sir Abacus
Member
Even if the textures and bandwidth are exactly the same from frame to frame the entire scene still needs to be streamed from the memory that the GPU is going to be rendering from to the GPU. For you to be able to render a scene in a certain amount of time (16ms for 60fps or 33fps for 30fps) you need to be able to supply all of the assets in a scene to the GPU from whatever memory it's rendering from.
Assume for this exercise you have unlimited GPU power (which compared to the 360 and PS3 GPUs might as well be true). We also make a lot of assumptions about latency which don't really apply in this scenario and assumptions about the GPU getting exclusive access to main memory which won't happen in the real world. This scenario is simplistic and a first approximation but basically works for illustrative puposes.
Let's assume we have 2GB of assets in a scene which is what developers are starting to push toward and will certainly hit this generation, at least on the PC side.
In the case of XB1, if you have 2GB of assets in a scene and the GPU can retrieve from main memory at 68GB/sec it's going to take 29ms for the bus to get the entire scene through the GPU. So you're going to be limited to 30fps by virtue of how long it takes the GPU to physically get the scene from memory to the rendering units.
What about the eDRAM? Well there's only 32MB of it. Nothing can make a 68GB/sec bus feed an eDRAM unit to transfer faster to the GPU. Streaming data to the GPU is purely how fast you can shove data down a pipe. Caches don't mean shit. It's basically good for frame buffer and AA and that's it.
The PS4 on the other hand is going to get the assets in the scenes streamed to the GPU in 11ms. So you can target 60fps or you can increase the amount of assets in the scene, make textures bigger, more geometry, etc. Memory bandwidth is almost certainly going to be the limiting factor as scenes push past 1GB stopping the XB1 from targeting 60FPS while the PS4 will still be cruising along with enough bandwidth to spare.
It might come down to shader throughput at some point too but I think we're going to see more games this generation which are 30fps on XB1 and 60fps on PS4 just by virtue of their memory bandwidth.
Angelus Errare
Banned
Math isn't really a strong suit of a few GAFers I see.
AgentP
Thinks mods influence posters politics. Promoted to QAnon Editor.
According to the leaked docs, the GPU can pull data from DDR3 and eSRAM in parelell for a theoretical max of 170GB/s.
But back to the OT, MS did the same fudging with the system bandwidth in the 360 on the Major Nelson 360 PS3 comparison article. They made the 360 bandwidth look massive by adding the eDRAM bandwidth (with compression) to the system RAM bandwidth.
Audioboxer
Member
cyberheater
PS4 PS4 PS4 PS4 PS4 PS4 PS4 PS4 PS4 PS4 PS4 PS4 PS4 PS4 PS4 PS4 PS4 Xbone PS4 PS4
That assumes that there is a single pool of main memory.
This image seems to state that there is a separate memory pool for the GPU. I don't know how accurate this image is:-
EDIT. Nope. I'm wrong. Just the ability to pull from the main memory and ESRAM at the same time. You're analysis is spot on.
The Friendly Monster
Member
I think you are doing a power of 2 to power of 10 conversion wrong somewhere. It is honestly as simple as 102+68 = 170.
dr_rus
Member
Yes, it can, but that gives you 170 GB/s for only 32 MBs of data, all the rest is just 68 GB/s. So you still cannot claim 170 GB/s for all of your RAM access.
According to the leaked docs, the GPU can pull data from DDR3 and eSRAM in parelell for a theoretical max of 170GB/s.
specialguy
Banned
you guys are assuming all the specs are exactly the same as the vgleaks posted to make this claim and none of you know that. microsoft did not reveal any clock speeds or any flop numbers to derive clock speeds from either. they did more or less confirm 768 shaders.
it's in the realm of possibility for example that a simple gpu upclock to 1ghz would boost the vgleaks diagram bw as is to 200gb/s with no other changes.
it's possible ms outright lied/fudged. it's also possible they did not.
it's in the realm of possibility for example that a simple gpu upclock to 1ghz would boost the vgleaks diagram bw as is to 200gb/s with no other changes.
it's possible ms outright lied/fudged. it's also possible they did not.
frankie_baby
Member
We don't actually know the speed of the Wii u's edram but the 2 best guess are either 70 or 140 but it has another separate pool as well
They didn't up anything.
PuppetMaster
Member
GPU clock has NOTHING to do with memory bandwidth. You are confused with FLOPs.
Memory bandwidth depends on memory clock and memory type. And we already have very good photos of their RAM chips. They are using Micron DDR3-2133
specialguy
Banned
the esram bw does.
this doesnt look good though since matt is some kind of insider.
Was going to post that, from what we know the vgleaks specs are spot on...
I still say the big deal will be whether AMD can get hUMA adopted for PC. Otherwise X1 will be the developers' low end platform and they may have minor improvements with PS4, depending on adoption rate. If AMD is successful then hUMA-PC's will become standard and X1 will take a back seat.
In the end PC always wins it's just a matter of whether PCs are the leader for graphical performance (as far as developers are concerned; ie, whether they target PCs first and downgrade the graphics or target consoles first and upgrade or not care about upgrading the graphics).
/drunk talking, grain of salt, corrections welcome, etc...
Actually, the reason Nintendo don't release specs since Wii is the exact same reason MS didn't release GPU specs this time around: because they are worse.
specialguy
Banned
actually why is the same reason microsoft wont say how many flops they have. it makes them look bad.
in Nintendo's case really really bad.
microsoft said 8 cores and 8gb ram, coincidentally the specs where they are equal to ps4.
edit:beaten
but then again in some video interview microsoft basically admitted 768 shaders i guess.
Infinite power of the cloud. All he has to say.
SirIgbyCeaser
Banned
Are there not organisations that protect us from major nelsons BS? Advertising falsehoods is kinda scary. Also it seems the esram exists only to pretend its faster than it really is. Yes first party devs for the xbone will be able to be creative with it but it will not solve the bandwidth issues between multiplatform games.
specialguy
Banned
break
I dont even know what to say about this. Are you serious? You do realize every company puts forth "favorable" numbers that are arguably fudged. Go back to Sony claiming PS3 had two teraflops...and making a bunch of cg vids at e3 2005 and saying they were gameplay.
Did sony have a major member of staff do a 4 part blog post on why they are better?.
nelsonroyale
Member
5 Billion transistors!
Rocket science.
This is kind of disingenuous. It's probably true for MS but Nintendo didn't release specs because the Wii/U wasn't intended to be sold on the promise of ray traced reflections.
It's a bit like saying the reason Fiat don't tout the 500's 0-62 time is because its worse than a BMW's. It's not at all, it's because it's not built for good acceleration and nobody buys it for that reason.
Individual photons bouncing off your watercooler.
BladeoftheImmortal
Member
shouldnt use the calcucorn for professional numbers.
Moral Panic
Member
lol was lazy, got caught
Your comparison doesn't really work: the Fiat 500's 0-100 times are right there in its spec list. Sure, they don't advertise it, but they also aren't completely withholding important information.
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