Predict: The Next Generation Console Tech

[SKYSONY]

bgassassin, whose post are always interesting to read, keeps saying the Durango´s GPU s will be less powerful than PS4 one. I thought he has mostly the same sources than lherre, but, apparently his info comes from a difference person.

It appears to me that the 720 dev kits (probably where all indiser info comes from) are constantly evolving, since back in November IGN said the GPU was a 6670, that is only 0.7 TFLOPS. If when bg got the > 1 TF info the dev kits were not the final ones, we might see a better number with the next leak.

 

[upnorthsox]

DDR3 is what CPUs use these days, so that's what it'll be. It's not a "step back". DDR3 can easily match or exceed the XDR memory bus of the PS3 today, and DDR3 chips are cheap, mass-produced commodity products while XDR remains extremely fringe (nevermind XDR2 which doesn't even exist except on paper, and maybe prototype form from what I understand.)

Actually DDR3 can't, and it only comes close with highly cherry-picked, extreme overclocked dimms with a pricetag that makes xdr seem like a bulk commodity item. And PS3 is only running it at half clock so the comp is even more one sided.

XDR2 should have been a stacked solution from the get go, especially in an LP variant. That was Rambus's big mistake, they misjudged where the market is going. They could've had Apple.

 

[Kb-Smoker]

Lherre saying leak ps4 specs were from last year. Amd just made some major improvements with rumor gpu so we could see some boost in performance just from this.

To begin with, AMD has worked with TSMC to refine the chip design. The Tahiti XT2 will be able to facilitate significantly higher clock speeds, at significantly lower voltages, than the current breed of Tahiti XT chips.

Tahiti XT2, or Radeon HD 7970 GHz Edition, will ship with a core clock speed of 1100 MHz, 175 MHz faster than the HD 7970. The GPU core voltage of Tahiti XT2 will be lower, at 1.020V, compared to 1.175V of the Tahiti XT.

big drop in voltage and raised clock speed.


http://www.techpowerup.com/167711/AMD-Radeon-HD-7970-GHz-Edition-quot-Tahiti-XT2-quot-Detailed.html

bgassassin, whose post are always interesting to read, keeps saying the Durango´s GPU s will be less powerful than PS4 one. I thought he has mostly the same sources than lherre, but, apparently his info comes from a difference person.

It appears to me that the 720 dev kits (probably where all indiser info comes from) are constantly evolving, since back in November IGN said the GPU was a 6670, that is only 0.7 TFLOPS. If when bg got the > 1 TF info the dev kits were not the final ones, we might see a better number with the next leak.

Well bg info is all second hand. Iherre is a proven game developing and info is first hand.

 

[tunafish]

Is there any benefit to XDR in stacked form? I don't know how the bus format affects stacked access.

There's a considerable downside -- DE buses are comparatively better the longer the traces need to be. In a stacked system, DE signaling is just a complete waste of silicon.

XDR2 should have been a stacked solution from the get go, especially in an LP variant. That was Rambus's big mistake, they misjudged where the market is going. They could've had Apple.

Rambus simply has no capability to design good stacked systems. Their strengths, in patents and experience, are in DE signaling and compensating for bad signal paths. None of that is useful for designing stacked memory systems.

 

[upnorthsox]

There's a considerable downside -- DE buses are comparatively better the longer the traces need to be. In a stacked system, DE signaling is just a complete waste of silicon.



Rambus simply has no capability to design good stacked systems. Their strengths, in patents and experience, are in DE signaling and compensating for bad signal paths. None of that is useful for designing stacked memory systems.

True, it would've been out of their comfort/expertise zone but better than being shut out completely.

 

[onQ]

DDR3 is what CPUs use these days, so that's what it'll be. It's not a "step back". DDR3 can easily match or exceed the XDR memory bus of the PS3 today, and DDR3 chips are cheap, mass-produced commodity products while XDR remains extremely fringe (nevermind XDR2 which doesn't even exist except on paper, and maybe prototype form from what I understand.)

& DDR2 is what CPUs used back when the PS3 was being designed & XDR didn't exist except on paper, and maybe prototype form.

Is there any benefit to XDR in stacked form? I don't know how the bus format affects stacked access.

There's a considerable downside -- DE buses are comparatively better the longer the traces need to be. In a stacked system, DE signaling is just a complete waste of silicon.



Rambus simply has no capability to design good stacked systems. Their strengths, in patents and experience, are in DE signaling and compensating for bad signal paths. None of that is useful for designing stacked memory systems.

Maybe Sony will stack the memory like they stacked it on the Vita SOC, where it's stacked on the chip but it's not TSV, & if XDR2 can achieve 32X Data Rate does it really need to be stacked using TSV?

wouldn't XDR2 be the perfect stop gap right now to achieve the bandwidth that they are going for with stacked ram?

or am I missing something?

 

[antwan]

& DDR2 is what CPUs used back when the PS3 was being designed & XDR didn't exist except on paper, and maybe prototype form.






Maybe Sony will stack the memory like they stacked it on the Vita SOC, where it's stacked on the chip but it's not TSV, & if XDR2 can achieve 32X Data Rate does it really need to be stacked using TSV?

wouldn't XDR2 be the perfect stop gap right now to achieve the bandwidth that they are going for with stacked ram?

or am I missing something?

XDR2 would be perfect, it will deliver a lot of bandwidth, even without stacking, that is correct.
It is expensive though, and like XDR before it, it has not yet been used so I don't know if it's certain to work like it's advertised..

 

[onQ]

XDR2 would be perfect, it will deliver a lot of bandwidth, even without stacking, that is correct.
It is expensive though, and like XDR before it, it has not yet been used so I don't know if it's certain to work like it's advertised..

Wouldn't that be the same case with Stacked Ram?


& also I see that XDR2 can go up to 4Gbit chips which is 512MB so they can fit 8 memory chips on a 256bit bus & have 4GB of Ram & achieve 409.6GB/s bandwidth.

but like you said price would be expensive.


PS: I really don't know much about this stuff but I'm a quick learner & this is what I got from reading about it so I could be way off with what I'm saying.

 

[Grall]

Actually DDR3 can't, and it only comes close with highly cherry-picked, extreme overclocked dimms with a pricetag that makes xdr seem like a bulk commodity item. And PS3 is only running it at half clock so the comp is even more one sided.

What on earth are you talking about? The 21ish GB/s that the PS3 XDR bus manages is extremely attainable with DDR3, without resorting to esoteric clock speeds.

 

[liolio]

My memory is telling me that latencies were far from great with xdram.
Anyway, this memory thing has been widely discussed in the proper thread I see no point going back there.

 

[antwan]

I imagine Kaz Hirai going to the Rambus' CEO, who is in the hospital and the CEO is saying something like:

We were in this together.. the state of the art PlayStation must return

Kaz:

what if he doesn't exist anymore?

CEO:

He must... he must

To me Rambus memory is what PlayStation has always been about. High-end. It would be a shame if they went with DDR3 or something like that, it will bite them in the long run, when they want to have the platform for +3 years..

 

[Grall]

Never heard anything bad about XDR's latencies. It's used in high-end routers and such which ought to be very latency-sensitive methinks. Old DRDRAM could have bad latency if many devices resided on the same memory channel, but in PS2 only had one device per channel, so latency was apparantly roughly comparable to regular SDRAM in that case.

 

[onQ]

What on earth are you talking about? The 21ish GB/s that the PS3 XDR bus manages is extremely attainable with DDR3, without resorting to esoteric clock speeds.

PS3 had 128bit main memory bus, DDR3 would have only been able to manage about 12GB/s in the PS3 & if the PS4 is 256bit DDR3 would only get about the same main memory bandwidth as the PS3 using 4 64bit 1GB DDR3 chips.


So it would be 4GB of memory in the PS4 but only about the same bandwidth as the PS3.


(That's if I'm doing this right.)

& with that same 256bit bus the PS4 could have 224GB/s (about 10 X the bandwidth of the PS3 ram) using 8 32bit 256MB GDDR5 chips for 2GB of ram.

or 409.6 GB/s (about 20 X the bandwidth of the PS3 ram) using 8 32bit 512MB XDR2 chips for 4GB of ram.

 

[Grall]

PS3 had 128bit main memory bus, DDR3 would have only been able to manage about 12GB/s in the PS3 & if the PS4 is 256bit DDR3 would only get about the same main memory bandwidth as the PS3 using 4 64bit 1GB DDR3 chips.

RSX in PS3 also has a 128-bit DDR3 memory bus, as do Xbox 360 btw and still reaches the same bandwidth.

So no, there's nothing magic about XDR in PS3... Even though it's only 64-bit in width it uses differential signaling, thus needing two pins per bit = 128 pins total for the full databus.

 

[onQ]

RSX in PS3 also has a 128-bit DDR3 memory bus, as do Xbox 360 btw and still reaches the same bandwidth.

So no, there's nothing magic about XDR in PS3... Even though it's only 64-bit in width it uses differential signaling, thus needing two pins per bit = 128 pins total for the full databus.

The RSX & Xbox 360 use GDDR3 not DDR3 unless I missed something.

 

[bkilian]

What on earth are you talking about? The 21ish GB/s that the PS3 XDR bus manages is extremely attainable with DDR3, without resorting to esoteric clock speeds.

in fact, the cheaper gddr3 on the 360 is 25.6GB/s.

 

[pjbliverpool]

PS3 had 128bit main memory bus, DDR3 would have only been able to manage about 12GB/s in the PS3 & if the PS4 is 256bit DDR3 would only get about the same main memory bandwidth as the PS3 using 4 64bit 1GB DDR3 chips.


So it would be 4GB of memory in the PS4 but only about the same bandwidth as the PS3.


(That's if I'm doing this right.)

& with that same 256bit bus the PS4 could have 224GB/s (about 10 X the bandwidth of the PS3 ram) using 8 32bit 256MB GDDR5 chips for 2GB of ram.

or 409.6 GB/s (about 20 X the bandwidth of the PS3 ram) using 8 32bit 512MB XDR2 chips for 4GB of ram.

You'll get 25.6 GB/s with 1600Mhz DDR3 on a 128bit bus. But you can get higher speed DDR3 than that.

 

[Grall]

The RSX & Xbox 360 use GDDR3 not DDR3 unless I missed something.

Whatever. It's not a difference that changes anything on a fundamental level.

 

[Kaotik]

Whatever. It's not a difference that changes anything on a fundamental level.

It changes quite a lot, GDDR3 is based on DDR2, and DDR3 is quite a bit different standard.

 

[onQ]

Whatever. It's not a difference that changes anything on a fundamental level.

Yes it does.