Consoles Vs PC bandwdith

[DavidGraham]

Alright, System Bandwidth for the PS4 is 176GB/s. Xbox One is 170GB/s . Average PCs no more than 25GB/s . Quad Channeled PCs could reach 68GB/s tops. In short Consoles have a HUGE advantage here .

How will that advantage translate into real world difference? Better and bigger textures on Consoles ? Less bottlenecks ?

Or will it just be a redundant advantage? We all know the difference between Dual and Quad channeled PCs is next to nothing in gaming scenarios.

 

[sebbbi]

Geforce GTX 680 (GDDR5) = 192 GB/s
Ivy Bridge (DDR3-1333) = 21 GB/s

Total = 213 GB/s.

Quite similar (~20% advantage to PC).

 

[DavidGraham]

Is combining video bandwidth with system bandwidth correct ? I am talking pure system bandwidth here.

 

[BRiT]

Yes, it is correct -- in the same way you combined system bandwidth for the Xbox One to get to 170GB/s. Certain builds of PCs have an advantage in terms of system bandwidth.

 

[DavidGraham]

I did so because I though the ESRAM on Xbox One could be accessed by both the CPU and GPU . From what you guys are saying I suppose it is only for the GPU.

If we strict the comparison to system bandwidth (CPU to RAM and Vice Versa) only.Then the PS4 is one hell of a bandwidth monster indeed . Can developers take advantage of that? If so in what way?

 

[Deleted member 13524]

Unlike gaming PCs with discrete graphics cards, the new-gen consoles use unified memory for CPUs and GPUs, so what PCs? What CPUs, what graphics cards?

Modern mid/high-end CPUs have a ton more L2 cache than the Jaguar cores in the xbone and ps4, and then they have L3 cache.

AFAIK the bandwidth makes more difference for a few computing operations and graphics processing. Modern mid/high-end graphics cards have well above 150GB/s. In fact, the latest HD7970 GE does 288GB/s.

As for the CPU, I find that my 5 year-old Phenom II @ 3GHz with a paltry 17GB/s DDR2 does as well in gaming benchmarks as similar systems using DDR3 memory that is twice as fast, so maybe the CPU doesn't really need more bandwidth.


If we're talking about PCs with APUs only, then we're not really talking about gaming PCs. At most, we're talking about PCs with some limited gaming capabilities.

Nonetheless, the next generation of APUs are already addressing the issue of increasing bandwidth for graphics processing. The top-end Haswell comes with 128MB of eDRAM, and there are talks about Kaveri bringing support for GDDR5 (specifics about replacing DDR3 with GDDR5 or creating a different channel of memory soldered in the motherboard are unknown to public AFAIK).

Further generations of APUs are expected to bring eDRAM under the form of stacked RAM or just increase the bandwidth with much faster DDR4.

 

[DavidGraham]

As for the CPU, I find that my 5 year-old Phenom II @ 3GHz with a paltry 17GB/s DDR2 does as well in gaming benchmarks as similar systems using DDR3 memory that is twice as fast, so maybe the CPU doesn't really need more bandwidth.

Yeah, my thoughts exactly , I am more inclined to believe these 176GB/s are dedicated mainly for the GPU with the CPU using only limited portions of it. Can the memory controller for the Jaguar cores even handle memory frequencies that high? highly unlikely .

 

[DJ12]

Fogive me if im wrong but I thought there was a leak saying there is 20 gb/s for the cpu to gddr5 allocation too on ps4 as well as 20gb/s from cpu to gpu directly.

First leaks did say 196gb/s which fits with the cpu to gddr5 bandwidth.

 

[warb]

I did so because I though the ESRAM on Xbox One could be accessed by both the CPU and GPU . From what you guys are saying I suppose it is only for the GPU.

If we strict the comparison to system bandwidth (CPU to RAM and Vice Versa) only.Then the PS4 is one hell of a bandwidth monster indeed . Can developers take advantage of that? If so in what way?

Not so much, it's shared bandwidth in the consoles, but the GPU will be using all but the relatively small amount the CPU requires. There doesnt seem to be anything special about the CPUs this time out.

 

[Grall]

Fogive me if im wrong but I thought there was a leak saying there is 20 gb/s for the cpu to gddr5 allocation too on ps4 as well as 20gb/s from cpu to gpu directly.

Yes, internal bus for CPU cores get 20-ish GB/s according to leaks, while PC CPUs can consume up to full main RAM bandwidth (minus system I/O of course.)

PS4 has 176GB/s because of the integrated GPU, naturally, which is a far larger consumer of bandwidth than CPU cores, which typically spend ~90-95% of their time inside their own L1/L2 caches.

 

[DavidGraham]

I need to double confirm this . You are really saying the CPU can access only 20 or so GB/s of the whole DDR5 memory bandwidth?

 

[sir doris]

I need to double confirm this . You are really saying the CPU can access only 20 or so GB/s of the whole DDR5 memory bandwidth?

Why would it need any more? It's the GPU that NEEDS the bandwidth, even 6 core 12 thread capable Intel CPUs don't really make much use of their quad core memory channels, which double the bandwidth available to the Sandy/ Ivy Bridge CPU's. What could a bunch of low power, low throughput Jaguar cores do with lots of bandwidth?

 

[MrFox]

Ivy Bridge has a "memory subsystem" of 252GB/s for the DDR3 + L1 + L2 + L3.

Of course that's crazy to add the CPU caches, but then we have to explain why a 32MB pool is counted as if it's the same thing as GBs of main memory.

 

[almighty]

My GPU alone has just over 350Gb/s bandwidth

 

[Esrever]

Ivy Bridge has a "memory subsystem" of 252GB/s for the DDR3 + L1 + L2 + L3.

Of course that's crazy to add the CPU caches, but then we have to explain why a 32MB pool is counted as if it's the same thing as GBs of main memory.

All cpu and gpu cores can access this bandwidth.

 

[Betanumerical]

All cpu and gpu cores can access this bandwidth.

Im not entirely sure the CPU's can access the eSRAM at full speed from the vgleaks diagram it seems that the eSRAM is hanging off the GPU memory subsystem. So the CPU would only be able to access it at 30GB/s max. Per the diagram.

 

[Grall]

So the GPU would only be able to access it at 30GB/s max. Per the diagram.

You mean CPU there, right? Anyway, since the CPU modules have only 20GB/s read/write connections to the northbridge, that could be a limiting factor as well. The coherent 30GB/s connection to the GPU may not be simultaneous read and write, if that is the case you can't break past the 20GB/s CPU access limit even though the link can do 30. Plus, there may be other traffic going over that CPU connection as well, there's four cores per module after all...

 

[Betanumerical]

You mean CPU there, right? Anyway, since the CPU modules have only 20GB/s read/write connections to the northbridge, that could be a limiting factor as well. Plus, there may be other traffic going over that CPU connection as well, there's four cores per module after all...

Indeed I do, thanks for the catch there.

I also just noticed the PCI-E mention on the peripheral devices, I find this odd.

 

[Grall]

Connection to south bridge chip is very likely PCIe.

 

[DavidGraham]

Im not entirely sure the CPU's can access the eSRAM at full speed from the vgleaks diagram it seems that the eSRAM is hanging off the GPU memory subsystem. So the CPU would only be able to access it at 30GB/s max. Per the diagram.

Is that diagram applicable for the PS4 too ?