Predict: The Next Generation Console Tech

[McHuj]

I think they're just referring to 3D rendering. I'm not sure how (or if) traditional memory buses will be feasible on shrinking geometries.

The way I see it you have the problem of needing a very wide bus running at a very fast speed. As you ramp up the clock, the IO will burn more and more power, probably disproportionately compared to the core. With shrinking geometries, the chips themselves will be pad limited as well. I think power wasted in IO will become a significant contributor to the overall power consumption.

If you look at a 7970 it has a bus width of 384 bits, 12 GDDR5 chips, and BW of 264 GB/sec. Let's assume that a 20nm, 9970 will double the performance of the 7970. I think memory BW will probably have to scale accordingly, but I don't think a 512+ bit bus at 7+ Gbps will really be doable (at least for a reasonably priced product, not some vanity card like a 7990)

Long term, it wouldn't surprise me to see all GPU's go with 2.5D stacking of memory. People say that the next gen consoles won't be bleeding edge, I think they will be, just not in raw performance, but the overall system architecture and the efficiency that it can achieve.

 

[almighty]

I think they're just referring to 3D rendering. I'm not sure how (or if) traditional memory buses will be feasible on shrinking geometries.

The way I see it you have the problem of needing a very wide bus running at a very fast speed. As you ramp up the clock, the IO will burn more and more power, probably disproportionately compared to the core. With shrinking geometries, the chips themselves will be pad limited as well. I think power wasted in IO will become a significant contributor to the overall power consumption.

If you look at a 7970 it has a bus width of 384 bits, 12 GDDR5 chips, and BW of 264 GB/sec. Let's assume that a 20nm, 9970 will double the performance of the 7970. I think memory BW will probably have to scale accordingly, but I don't think a 512+ bit bus at 7+ Gbps will really be doable (at least for a reasonably priced product, not some vanity card like a 7990)

Long term, it wouldn't surprise me to see all GPU's go with 2.5D stacking of memory. People say that the next gen consoles won't be bleeding edge, I think they will be, just not in raw performance, but the overall system architecture and the efficiency that it can achieve.

There's a few Kepler cards that are running overclocked GDDR5 at 7Ghz or slightly over.

There's some 7970's doing over 6Ghz GDDR5 so I don't think 512bit with 7Ghz GDDR5 would be that difficult.

 

[lefizz]

Difficult quite i would think, but doable.

However it would severely limit their ability to shrink the chips and would make motherboards much more expensive through the lifecycle of the product.

So it isn't going to happen

Things that make the initial launch product expensive may be allowed, think blu-ray drives, but things that will make the product expensive for its entire production run won't happen because its flies against even basic economics.

 

[MrFox]

There's a few Kepler cards that are running overclocked GDDR5 at 7Ghz or slightly over.

There's some 7970's doing over 6Ghz GDDR5 so I don't think 512bit with 7Ghz GDDR5 would be that difficult.

But super expensive. There's been the argument that WideIO-2 might not be ready in time, but the Vita proves that Sony can do it, they didn't wait for the final specs and used WideIO before it was ready. Why can't they do that for the PS4?
I think WideIO-2 might be ready in time, it would be much less expensive, much less power hungry, and easier to reduce cost later on. No issue with pad area. At 1066Mhz, it's 125MB/s per chip, so 4 chips would be 500MB/s.

 

[3dcgi]

512bit bus is not incredibly high btw, it's what Intel uses on Haswell GT3. But Intel uses slow memory.
Why that number, how is it known?

There's no way Haswell will have a 512 bit external memory bus.

 

[MfA]

But super expensive. There's been the argument that WideIO-2 might not be ready in time, but the Vita proves that Sony can do it

Chip on chip stacking is not new, without TSVs it's only useful for very small amounts of memory (Sony did not use TSVs). Not worth the trouble it will cause for cooling with higher power ICs.

TSV technology/reliability and cooling are the limiting factors in 3D integration ... and even 2.5D integration (because to keep the interposer affordable the memory still has to be true 3D stacked).

 

[MrFox]

Chip on chip stacking is not new, without TSVs it's only useful for very small amounts of memory (Sony did not use TSVs). Not worth the trouble it will cause for cooling with higher power ICs.

TSV technology/reliability and cooling are the limiting factors in 3D integration ... and even 2.5D integration (because to keep the interposer affordable the memory still has to be true 3D stacked).

Okay, following that train of thought, is a CoC really out of the question?
Heat might be manageable if the bottom layer is the GPU and is on the heat-sink, and the top layer is the memory. (I thought the unsolved issue with 3D was the "more than 2 layers" heat management)

 

[almighty]

I really think PS4 and 720 will not use chip stacking, they'll be separate chips because of heat issues.

 

[Grall]

There's no way Haswell will have a 512 bit external memory bus.

He's referring to the on-substrate DRAM module, not regular motherboard DIMM memory.

I'd be rather surprised actually if the DRAM "only" has a 512-bit bus, I would more or less have expected 1kbit...

 

[BobbleHead]

For the interposer / MCM, it could be an option. Actually looking at Nintendo which made that choice

An MCM and a 2.5D interposer are significantly different from each other, with big differences in cost and performance. I would not lump the two together like that.

The original Wii chip was an MCM with memory on the same package as the GPU.

 

[MfA]

Traditionally speaking an organic substrate is an interposer as well, so traditionally a MCM could use an interposer ... modern short hand is to reserve the term only for silicon and glass interposers, but it's not really a great idea.

 

[Cyan]

This is just the market research firms speculation, but it's as good as any. The pictured chip looks the same as the one that had been shown previously on Semiaccurate.

Judging from the picture it looks like the design of the PS4 is certainly up to the minute. It sounds like that new technology from Intel called tri-3D or something like that, if my memory serves me correctly.

If it has a good selection of games from the very beginning, adding to this the PlayStation brand in it, it could compete pretty well with the WiiU and the Xbox 720. Let's see how things pan out.

 

[DieH@rd]

Judging from the picture it looks like the design of the PS4 is certainly up to the minute. It sounds like that new technology from Intel called tri-3D or something like that, if my memory serves me correctly.

Intel is making 3D transistors, not 3D chip stacking.
http://www.youtube.com/watch?v=YIkMaQJSyP8&feature=player_embedded#t=133s

 

[Kaotik]

Intel is making 3D transistors, not 3D chip stacking.
http://www.youtube.com/watch?v=YIkMaQJSyP8&feature=player_embedded#t=133s

TSMC and GF will be doing those too, I think they (both) dub 'em "FinFETs"

 

[Gipsel]

TSMC and GF will be doing those too, I think they (both) dub 'em "FinFETs"

And intel will also do stacking (for instance with Haswell GT3).

 

[Grall]

Not stacking; just side-by-side bog standard multi-chip module. Not fundamentally any different than say, the Pentium 4 D for example, or Core2 Quad CPUs from a number of years ago.

 

[Gipsel]

Not stacking; just side-by-side bog standard multi-chip module. Not fundamentally any different than say, the Pentium 4 D for example, or Core2 Quad CPUs from a number of years ago.

You think they will route a 512 Bit wide memory interface over the organic substrate of an MCM? And how much die size for the pads would this cost?

 

[Blazkowicz]

Pentium D or Core 2 Quad actually didn't even talk to each other, they did it through the FSB (there's VIA Nano X4 doing the same thing)
Better is the Opteron on socket G34, but dies just talk through Hypertransport which is not a very wide interface.

Closer to stacking, and an early example would be the Pentium Pro but maybe it's just a crazy regular MCM. Cost be damned, they just wanted to make the fastest CPU on Earth (it was, on par with the fastest Alpha) and make it good for SMP.
http://en.wikipedia.org/wiki/Pentium_Pro#An_innovation_in_cache

 

[Gipsel]

Pentium D or Core 2 Quad actually didn't even talk to each other, they did it through the FSB (there's VIA Nano X4 doing the same thing)
Better is the Opteron on socket G34, but dies just talk through Hypertransport which is not a very wide interface.

Closer to stacking, and an early example would be the Pentium Pro but maybe it's just a crazy regular MCM.

Yes, it was an MCM. And what was the width of the cache interface of the PentiumPro? 64 bits? Still a far cry from the 512 bits of Haswell GT3.

 

[Rangers]

Hot new post from "sweetvar26" at GAF. BG seems to think his info is legit in the past.

http://www.neogaf.com/forum/showthread.php?p=43335723#post43335723

Alright, I'm in Toronto and was talking to my buddy who works at the AMD headquarters here.

As of what he tells me, they both are using same chip with different specifications from Sony and Microsoft, something like the market's 7700-7800, not really sure. He did mention the word "Jaguar processor".

As for the PS4, the first chip has already been sent out two months ago, it is back after a month or so, for the second revision. He says there should be a third and if they don't see any problems, should be ready for mass production. Apparently, AMD did delay the work, he says it is around 6 months behind schedule.

The Xbox 720/loop or whatever it is called, they are about to ship the chip tomorrow, they are expecting it back within a month or so for the second revision. Xbox is right on time, no delays so far. A feature for the Xbox that the PS4 doesn't have is something related to "ARM security". I did not get that part. However the internal talk at AMD is that, the Xbox is like a super computer(not sure if it is the chip or the console). Him and the team at AMD feels the Xbox is going to be more 'powerful'.

I did ask him to find out what the market equivalent card would the chips be, he said he will. Apparently the Xbox 720 team is sponsoring for lunch and a movie today(Looper), they are about to ship the first chip out tomorrow and they are expecting it back within a month for more revisions. He believes both the consoles should be out next fall, not far from each other.

P.S. He does not play games nor does he know anything about them. So he isn't as curious as you and I are.