GDDR5 vs DDR3 in PS4

[aknbad23]

Ok, I know GDDR5 is better, faster, etc, but what about power consumption? Will it run hotter and draw more power than DDR3?

 

[KeithTalent]

http://forums.anandtech.com/showthread.php?t=2301892

KT

 

[RobDickinson]

GDDR is similar to DDR but optimised for bandwidth.

So the PS4 will have lots of bandwidth for graphics. But it looses out on latency so the cpu will suffer some.

The weird thing is the info on the gpu being limited to 2gb of the gddr5, that doesnt make sense.

The best option would be mix it but the AMD APU (gpu+cpu+memory controller) only has 1 memory controller so cant do both.

 

[EightySix Four]

GDDR is similar to DDR but optimised for bandwidth.

So the PS4 will have lots of bandwidth for graphics. But it looses out on latency so the cpu will suffer some.

The weird thing is the info on the gpu being limited to 2gb of the gddr5, that doesnt make sense.

The best option would be mix it but the AMD APU (gpu+cpu+memory controller) only has 1 memory controller so cant do both.

Who said the GPU can only access 2gb?

 

[RobDickinson]

Its in the Arstechnica articles. Though they arnt certain.

 

[badb0y]

It's 8GB of unified memory. The OS reserves 1GB for itself the rest is free for all.

 

[-Slacker-]

Will the cut down hd 7870 inside the ps4 be able to ever use more than 4 gb of gdd5 as a vram buffer? Because, if not, the extra 4 gb of gddr5 was entirely superfluous and only serve to bloat the price.

 

[Pottuvoi]

Will the cut down hd 7870 inside the ps4 be able to ever use more than 4 gb of gdd5 as a vram buffer? Because, if not, the extra 4 gb of gddr5 was entirely superfluous and only serve to bloat the price.

Memory is 'unified' so all memory after OS and actual program data is usable by GPU.
Basically you can have 'simple' game with over 7GB of memory used by the GPU.

 

[-Slacker-]

Memory is 'unified' so all memory after OS and actual program data is usable by GPU.
Basically you can have 'simple' game with over 7GB of memory used by the GPU.

I meant that it should have 4 gb of vram and 4 gb of system ram (ddr3 or whatever) if it doesn't ever need more than a 4 gb vram buffer. Not to say that I'm sure it can't use more, I'm just a bit skeptical, when even crysis 3 won't use more than 1.6 gb of vram at 1080p, vhq with 4xmsaa - and that's a 30 fps showing on a hd 7970GE.

So how will a severely cut down hd 7870 manage to clog up more than 4 gb of gddr5 at 30 fps (much less 60 fps)?

 

[kami]

I meant that it should have 4 gb of vram and 4 gb of system ram (ddr3 or whatever) if it doesn't ever need more than a 4 gb vram buffer. Not to say that I'm sure it can't use more, I'm just a bit skeptical, when even crysis 3 won't use more than 1.6 gb of vram at 1080p, vhq with 4xmsaa - and that's a 30 fps showing on a hd 7970GE.

So how will a severely cut down hd 7870 manage to clog up more than 4 gb of gddr5 at 30 fps (much less 60 fps)?

They tried the discrete system and video memory in the PS3 and developers did not like it. They preferred the unified approach of the 360 (which used unified GDDR3).

GPU power is the most important factor in a console anyway. The GPU in the ps4 can also be utilized for non-graphics computing when needed. They demonstrated it doing physics processing as one example.

 

[Aikouka]

They tried the discrete system and video memory in the PS3 and developers did not like it. They preferred the unified approach of the 360 (which used unified GDDR3).

I'm not so sure that it was the setup that the developers didn't care for but rather the size limitations that were imposed by the 256MB headroom vs. a shared 512MB. It would be interesting to see how much of the CPU's 256MB went unused, and what the GPU's memory usage was at.

I would imagine that unified memory can present some negative aspects as well. I've never coded on such a low level, but I would guess that if the CPU and GPU tried to access a piece of memory at the same time, someone would have to wait. That is unless the memory controller segments separate calling entities (CPU, GPU, etc.) to different DRAM modules, which may allow it to fulfill calls from multiple entities at once. I sort of see this as the reverse of a SSD, which purposefully breaks data down to stripe it across as many NAND chips, which then speeds up retrieval (each NAND chip + NAND bus can only operate at a certain rate) and also helps ensure good wear leveling.

 

[-Slacker-]

They tried the discrete system and video memory in the PS3 and developers did not like it. They preferred the unified approach of the 360 (which used unified GDDR3).

GPU power is the most important factor in a console anyway. The GPU in the ps4 can also be utilized for non-graphics computing when needed. They demonstrated it doing physics processing as one example.

My main concern here is cost, as opposed to some vague performance or convenience of programing gains... 8 gb of gddr5 costs what ... like $100? Whereas 4 gb of gddr5 plus 4 of ddr3 would be close to $60.

 

[lamedude]

They tried the discrete system and video memory in the PS3 and developers did not like it. They preferred the unified approach of the 360 (which used unified GDDR3).

They complained about the UMA on the N64 and Xbox so don't blame Sony for listening for once. If Sony was aiming for 1080P eDRAM would of been to expensive.

It would be interesting to see how much of the CPU's 256MB went unused, and what the GPU's memory usage was at.

RSX can read Cell's XDR at a descent speed so if you had bandwidth to spare you could put textures there. Its the other way that not doable since Cell can only read GDDR3 at 16MBps "(no, this isn't a typo...)".

 

[RobDickinson]

Theres no need for the CPU to have GDDR5.

Theres little need (if any) for the GPU to have more than 2-3gb of GDDR5. Rememebr its going to be pushing 1080p max gaming resolution (1920x1080).

4GB GDDR5 would have been enough, adding 2GB DDR3 would have been nice but with the APU platform its also unpossible (within reason).

 

[Pottuvoi]

I'm not so sure that it was the setup that the developers didn't care for but rather the size limitations that were imposed by the 256MB headroom vs. a shared 512MB. It would be interesting to see how much of the CPU's 256MB went unused, and what the GPU's memory usage was at.

What I have heard none of the main memory went ununsed.
Actually lack of main memory was serious problem to many developers. (~200MB usable main memory isn't that much.)

 

[Dranoche]

Theres no need for the CPU to have GDDR5.

Theres little need (if any) for the GPU to have more than 2-3gb of GDDR5. Rememebr its going to be pushing 1080p max gaming resolution (1920x1080).

4GB GDDR5 would have been enough, adding 2GB DDR3 would have been nice but with the APU platform its also unpossible (within reason).

There are a few games that benefit from having a 2GB card over a 1GB card on PC right now, specifically games with very large environments. Some of the recent GPU reviews here on AT have mentioned it, pointing out some of the newer games that sometimes benefit from the extra memory. There's no need for it now, but that was kind of the issue with the PS3 and 360 - they didn't need it then but they sure could use it now. With most games now only running natively at 720p on consoles, you can bump that up to 1080p and increase texture resolutions and AA, all with larger environments, and still have headroom for the future. I suppose this will give the system a bit more longevity before developers have to start dipping into the black magic hat to make things work.

With the APU will the higher latency of the GDDR5 matter less? And maybe its cheaper to just use all GDDR instead of trying to use different memory for the CPU and GPU. Is that even possible?

 

[RobDickinson]

All things are possible! It could well be expensive though adding a new memory controller and probably means splitting ram so no unified memory.

Sure 2gb is nice for a few games, at what resolution? Remember this will be locked to 1080 max, perhaps 2gb is a sensible amount for 1080 with AA and effects etc. Also remember the GPU wont have the power to do much more either. So far game engines on PC havnt needed over 2gb either and are less efficient than console games. 4GB total would have been plenty IMO.

Graphics 'pop' is more to do with draw distances, polygons and pixel fill rates than being able to store textures in gpu memory.

 

[Dari]

Will the cut down hd 7870 inside the ps4 be able to ever use more than 4 gb of gdd5 as a vram buffer? Because, if not, the extra 4 gb of gddr5 was entirely superfluous and only serve to bloat the price.

Theres no need for the CPU to have GDDR5.

Theres little need (if any) for the GPU to have more than 2-3gb of GDDR5. Rememebr its going to be pushing 1080p max gaming resolution (1920x1080).

4GB GDDR5 would have been enough, adding 2GB DDR3 would have been nice but with the APU platform its also unpossible (within reason).

All things are possible! It could well be expensive though adding a new memory controller and probably means splitting ram so no unified memory.

Sure 2gb is nice for a few games, at what resolution? Remember this will be locked to 1080 max, perhaps 2gb is a sensible amount for 1080 with AA and effects etc. Also remember the GPU wont have the power to do much more either. So far game engines on PC havnt needed over 2gb either and are less efficient than console games. 4GB total would have been plenty IMO.

Graphics 'pop' is more to do with draw distances, polygons and pixel fill rates than being able to store textures in gpu memory.

You guys are assuming that the PS4, which is coming out at the end of 2013, is being made for today's gaming. SONY has given itself and developers massive room to develop entertainment for the next 10 years, not just for 2013...

 

[cmdrdredd]

You guys are assuming that the PS4, which is coming out at the end of 2013, is being made for today's gaming. SONY has given itself and developers massive room to develop entertainment for the next 10 years, not just for 2013...

Right, I think the goal was to have enough for the life of 1080p, and when 4k is standard, they up the power on the CPU and GPU using the tech at the time and they go from there, easily allowing PS4 games to be upscaled on 4k TVs using the PS5 and PS5 games being way beyond what we can do today in terms of pure scale.

It may be a bit under powered vs a custom PC, but it doesn't necessarily need to be loaded up like my sig. When the overhead is so low and optimizations can be much more rewarding.

 

[crisium]

It may be overkill, but that's not a bad thing. This might be the first console to ever not be limited by memory. The PS1 generation actually had multiple forms of memory expansion because games were starved for it.

Most total system memory:

1. 8.5MB - Sega Saturn with 4MB Expansion
2. 8MB - N64 with 4MB Expansion
3. 5.5MB - Sega Saturn with 1MB Expansion
4. 4.5MB - Sega Saturn
5. 4MB - N64
6. 3.5MB - PS1

The system with already the most default memory was given an expansion. Then they gave it ANOTHER. The N64 also doubled it's memory.

So about 4MB of ram was the average. Next generation:

1. Xbox - 64MB
2. Gamecube - 43MB
3. PS2 - 36MB (including
4. DC - 26MB

Microsoft's insistence on DX (DirectXbox was the original name) actually hurt the Xbox 1, as I recall at least one developer actually saying they had more room to work with the PS2. You could also solder on an extra 64MB on the Xbox 1 if you wanted to at home, perhaps a sign that MS once considered 128MB (probably for more 720p games). The weakest console, the Dreamcast, also had some RAM issues. It was essentially an arcade machine at home, except the NAOMI had more than double the RAM (56MB total). Some ports suffered from this.

Then this generation the Xbox 360 has 522MB (including EDRAM) and the PS3 has 512MB. It's no secret RAM holds these back tremendously. Battlefield 3 suffers the most, see 24 vs 64 players.

4GB of memory might have held back the PS4 in 5+ years. I applaud Sony for basically going with an "Expansion Pak" at launch. N64 should have done it at launch, and despite the high prices the current gen could have really used 1GB.

PS1 to PS2 - 10.3X memory increase
PS2 to PS3 - 14.2X memory increase
PS3 to PS4 - 16X memory increase

It makes sense.

Now 4GB GDDR5 + 4GB DDR3 would been cheaper, of course. But it would have been harder to program for especially when games eventually start using more than 4096MB. This is simple, which developers love.

 

[RobDickinson]

You guys are assuming that the PS4, which is coming out at the end of 2013, is being made for today's gaming. SONY has given itself and developers massive room to develop entertainment for the next 10 years, not just for 2013...

PS4 will only have enough graphics power to push 1080 games. it may be able to do 4k video and images but it wont do 4k gaming.


'It may be overkill, but that's not a bad thing'.

If 4GB of DDR5 sits in the console unused for its life then its wasted cost and expense.

 

[Red Hawk]

PS4 will only have enough graphics power to push 1080 games. it may be able to do 4k video and images but it wont do 4k gaming.


'It may be overkill, but that's not a bad thing'.

If 4GB of DDR5 sits in the console unused for its life then its wasted cost and expense.

Screen resolution is not the only thing that memory is used for, especially considering this is a unified memory pool and not just graphics memory. High resolution textures, antialiasing, larger gameplay areas, geometry, etc.

The current generation of consoles ran headlong into a memory size and bandwidth wall. Like crisium, I applaud Sony for taking this measure to help ensure that doesn't happen this time around. Would've been nice if they had used a memory type that was faster than what PCs have been using for the past 4 years or so, but oh well...

 

[zerocool84]

PS4 will only have enough graphics power to push 1080 games. it may be able to do 4k video and images but it wont do 4k gaming.


'It may be overkill, but that's not a bad thing'.

If 4GB of DDR5 sits in the console unused for its life then its wasted cost and expense.

If it didn't need it they wouldn't have put it in it. There's going to be much more going on in the background than previous consoles.

 

[ViRGE]

Microsoft's insistence on DX (DirectXbox was the original name) actually hurt the Xbox 1, as I recall at least one developer actually saying they had more room to work with the PS2. You could also solder on an extra 64MB on the Xbox 1 if you wanted to at home, perhaps a sign that MS once considered 128MB (probably for more 720p games).

Development consoles typically have extra RAM for debugging purposes. The pads for that extra RAM are sometimes left.

 

[VirtualLarry]

Perhaps the added expense was having a seperate GDDR5 memory controller, alongside another DDR3 memory controller. Perhaps the additional number of I/O pins for that would have negated the cost savings from going with half GDDR5/DDR3.

Perhaps Sony is hoping to avoid the additional cost of DDR3, once they stop making it, as the industry moves on to DDR4 in the next year or so? Whereas, there is still likely to be a good supply of GDDR5 in the channel for a long time to come.

Could you imagine if the PS3 used DDR2 memory, and the price of said memory went up?