RSX architecture and cost...

[AlNom]

Is that a photo from a launch unit?

With respect to a reduction in memory speed, I would be more inclined to believe it was a heat issue rather than a chip issue per se. Samsung offers 1.429ns (700MHz) or 2.0 ns (500MHz) GDDR3 - since they've been using properly rated RAM chips, it doesn't make any sense to clock them lower other than for heat output reasons IMHO; they're certainly not going to care about battery life.

edit:

Note: they also offer higher speeds (1.25ns, 1.1ns, 1.0ns), but they're irrelevant here.

 

[Crossbar]

Is that a photo from a launch unit?

Yes, that picture is from a teardown of a launch unit.

http://pc.watch.impress.co.jp/docs/2006/1111/ps3.htm

 

[Carl B]

I can understand your logic that if the circuits were capable of higher speed they should be running at that speed right out of the gate.

Exactly.

But I have seen some convoluted logic motivating different decisions before, so I don´t take anything for granted.

And that logic is just that: convoluted. And it generally originates with those that for the longest time wouldn't believe the 500Mhz downclock to begin with. Why would Sony hold back? I'm certainly happy to hear any viable theories on the subject.

 

[Shifty Geezer]

Yes, that picture is from a teardown of a launch unit.

http://pc.watch.impress.co.jp/docs/2006/1111/ps3.htm

You'd need a pic from a recent system to see if they've kept the 700 MHz RAM or gone with 500 MHz. It could be that after contracting an order of 700 MHz, Sony decided the long-term price would be too high, so went with 500 MHz, using up the 700 MHz chips they had and then dropping to cheaper stuff for later. It's also worth noting that they've used 700 MHz RAM when the clockspeed was set to 550 MHz anyway. The RAM clock-speed clearly isn't indicative of intended speeds. Could be that the supplies are rated either up to say 450 MHz or 700 MHz, and Sony had to get the faster stuff even if they weren't going to run it at maximum speed.

 

[swaaye]

Even if they bumped it to 550 MHz, that's only a 10% boost to core clock. So, at best, you're going to see a 10% speed increase. Obviously it never works quite like that because overall performance is a combination of GPU core clock, GPU RAM clock, and general system performance, so the resulting few % gain wouldn't even be noticeable. Even if they bumped the GPU RAM clock 10% too, unless the GPU is 100% the bottleneck, it wouldn't give you a 10% speed increase.

 

[Thowllly]

You'd need a pic from a recent system to see if they've kept the 700 MHz RAM or gone with 500 MHz. It could be that after contracting an order of 700 MHz, Sony decided the long-term price would be too high, so went with 500 MHz, using up the 700 MHz chips they had and then dropping to cheaper stuff for later. It's also worth noting that they've used 700 MHz RAM when the clockspeed was set to 550 MHz anyway. The RAM clock-speed clearly isn't indicative of intended speeds. Could be that the supplies are rated either up to say 450 MHz or 700 MHz, and Sony had to get the faster stuff even if they weren't going to run it at maximum speed.

I think you're mixing up the core speed and the ram speed. The ram runs at 650Mhz AFAIK

 

[orionthehunter]

And that logic is just that: convoluted. And it generally originates with those that for the longest time wouldn't believe the 500Mhz downclock to begin with. Why would Sony hold back? I'm certainly happy to hear any viable theories on the subject.

I happened to agree with Crossbar that companies logic, at times at least, appears to be convoluted, however you asked to hear theories. The only halfway logical idea I can think of is that they downclocked the RSX and the VRAM because the additional heat put them too close to the threshold of the next fan speed. At the time of launch, the noisiness of the 360 was a big deal and Sony may have wanted to avoid that, especially since it was one of the things that was said about the PS2 at launch. Also, given that the RSX was the first 90nm G70/1 variant and that if memory serves the the G71 was around 625mhz, its possible that RSX isn't hardware limited to 550mhz either, but this is pure speculation, not to be taken too seriously.

For a PSP-esque clock speed increase to occur the PS3, can't be hardware limited, and whatever reason that caused them to believe the downclocking was needed has to be overshaded by the customer bases desire for more power or at least see the downside as a non-factor, as is believed to be the case with the PSP. In short, I don't believe it will happen, if its even possible, until the 65nm boards dominate the install base, as their, smaller components should make the above explanation a non-issue.

 

[Carl B]

I happened to agree with Crossbar that companies logic, at times at least, appears to be convoluted, however you asked to hear theories. The only halfway logical idea I can think of is that they downclocked the RSX and the VRAM because the additional heat put them too close to the threshold of the next fan speed. At the time of launch, the noisiness of the 360 was a big deal and Sony may have wanted to avoid that, especially since it was one of the things that was said about the PS2 at launch. Also, given that the RSX was the first 90nm G70/1 variant and that if memory serves the the G71 was around 625mhz, its possible that RSX isn't hardware limited to 550mhz either, but this is pure speculation, not to be taken too seriously.

Well, I'll grant that it's a theory that at least would not run counter to reality. I personally do not buy into it, but I think I've made that clear up until now.

 

[ArturNOW]

I have one question as you spend a lot of time comparing GPU of both consoles, talking a lot about vertex shaders in RSX. But isn't it that Sony put RSX on PS3 only to get quite good looking games very fast because a lot of developers are familiar with GPU programming? And they were planing to put only CELLs to do everything. So in PS3 a lot of rendering will be handled by RSX but also by CELL. In this generation programmers with get familiar with SPU programming and in PS4 we will see only few next-get CELL processors maybe 2, maybe 4 will see? I would like to know if it make any sense to compare GPUs of both console as CELL is quite powerfull in rendering and in time games will use more and more SPU??

 

[V3]

Is the game designed for 333 MHz (thus TRC'ed for all PSP's both Phat and Slim ) ? Is the game running at 333 MHz due to homebrew enabled overclocking ?

Well the one with the firmware that can run homebrew is fine. Its the one that had the latest firmware that can freeze playing the newer games. Traded with the slim so its all well now.

 

[Crossbar]

Well, I'll grant that it's a theory that at least would not run counter to reality. I personally do not buy into it, but I think I've made that clear up until now.

That would have been my first theory of choice, because it rhymes with the PSP battery story. I could combine it with a couple of others as well, but I don´t think anything good would come out from that discussion and some of you probably know from before one of my favourite convoluted theories. Sony keeping some superior control of game evolution to stepwise prolong the attraction and life-cycle of the system etc. i.e. somewhat delay the ramp-up and the peak of game visuals and perhaps make the developers concentrate on the power of Cell instead of just making a half-ass port of the 360 GPU-code. Oops there I said it.

Anyway how many of you would have thought that Sony would completely remove the frequency restriction of the PSP games that was imposed to save batteries? Anyone presenting such a theory would probably have been declared mad one year ago.

With respect to a reduction in memory speed, I would be more inclined to believe it was a heat issue rather than a chip issue per se. Samsung offers 1.429ns (700MHz) or 2.0 ns (500MHz) GDDR3 - since they've been using properly rated RAM chips, it doesn't make any sense to clock them lower other than for heat output reasons IMHO; they're certainly not going to care about battery life.

A 50 MHz speed difference for the 256 MB GDDR3 probably accounts for less than 1 W of heat output. Keeping the RAM speed proportional to GPU speed would simplify bumping up the speed one day in the future since it wouldn´t screw up all the GPU code that have been carefully optimized with regard to the speed of the RAM pipeline.

 

[Shifty Geezer]

Anyway how many of you would have thought that Sony would completely remove the frequency restriction of the PSP games that was imposed to save batteries? Anyone presenting such a theory would probably have been declared mad one year ago.

Not at all, because the hardware announced as 333 MHz and we were informed it was capped at 222. They even said, though I don't remember when in PSP's life cycle, that the clock speed could be improved in future with the availability of better batteries making up for power draw. This is in contrast to PS3 where we've been told (back of the box specifications) that the GPU is clocked at 500 MHz and not 1-550 MHz or something similar to PSP's listed clockspeed.

 

[AlNom]

Keeping the RAM speed proportional to GPU speed would simplify bumping up the speed one day in the future since it wouldn´t screw up all the GPU code that have been carefully optimized with regard to the speed of the RAM pipeline.

Proportional? They're both completely different clock speeds. How does higher bandwidth screw up anything ? Lowering the bandwidth would screw things over more.

As Shifty has pointed out earlier, Sony may not be using 700MHz RAM, and are instead overclocking slower rated RAM. At that point 50MHz, can be significant.

 

[Crossbar]

Proportional? They're both completely different clock speeds. How does higher bandwidth screw up anything ? Lowering the bandwidth would screw things over more.

As Shifty has pointed out earlier, Sony may not be using 700MHz RAM, and are instead overclocking slower rated RAM.

If you optimze for a low bandwidth and suddenly get higher GPU speed but keep the same low bandwidth your optimization will not be optimal anymore, but if the memory speed is increased proportionally (or close to proportional) your optimization will remain pretty optimal. What is wrong in that logic?

BTW Pretty close to proportional IMO, but I was careless not to insert an "close to" in front of proportional:
50/550 = 0.091 50/700 = 0.071, a 2 percent difference on the overall clock speed.

Using 50 MHz steps on both may help data synch or such, it may have been the closest they could get or they just prefered using even and nice numbers.

Do we have any hard data that Sony started using differently speced memory modules?
I think 700 MHz GDDR3 must be the sweet spot pricewise. If not, why are all three current gen consoles: Wii, 360 and PS3 using them? It almost seems like they made a deal. :smile:

 

[AlNom]

If you optimze for a low bandwidth and suddenly get higher GPU speed but keep the same low bandwidth your optimization will not be optimal anymore,

But we're not getting a faster GPU or even faster memory. They were expecting 700MHz memory and a 550MHz GPU. The GPU clock speed was reduced. Why was the memory speed reduced if they had 700MHz-rated memory? That's the issue.

but if the memory speed is increased proportionally (or close to proportional) your optimization will remain pretty optimal.

Well, yeah... that's what I'm saying. There's no reason to decrease the memory bandwidth.

I'm not sure what you're saying now.

edit: oh wait, you're still talking about Sony increasing speeds in the future. It's not the same situation as with PSP.

 

[Crossbar]

Not at all, because the hardware announced as 333 MHz and we were informed it was capped at 222. They even said, though I don't remember when in PSP's life cycle, that the clock speed could be improved in future with the availability of better batteries making up for power draw.

If Sony said that, it´s complete news to me. If you could supply a link I would be really interested in reading it. Didn´t they supply fat long-life batteries right after launch?

This is in contrast to PS3 where we've been told (back of the box specifications) that the GPU is clocked at 500 MHz and not 1-550 MHz or something similar to PSP's listed clockspeed.

Does it really say 500 MHz on the box of the PS3? That would also be news to me, I thought they removed all clock fequencies from the official specs at the time of the launch of the PS3, even for Cell.

 

[Crossbar]

Well, yeah... that's what I'm saying. There's no reason to decrease the memory bandwidth.

I'm not sure what you're saying now.

Whatever, to be more specific in my convoluted theory. Both memory and GPU speed were both similarly reduced to ease the life of the GPU code wizards (the ones counting IPC and latencies) once the system returns to the original spec. i.e. all their hard-earned experiencies would still be valid.

 

[Cornsnake]

The box for the PS3 doesn't have the GPU speed on it. My preorderkit did and it still said 550 MHZ.

 

[Butta]

That would have been my first theory of choice, because it rhymes with the PSP battery story. I could combine it with a couple of others as well, but I don´t think anything good would come out from that discussion and some of you probably know from before one of my favourite convoluted theories. Sony keeping some superior control of game evolution to stepwise prolong the attraction and life-cycle of the system etc. i.e. somewhat delay the ramp-up and the peak of game visuals and perhaps make the developers concentrate on the power of Cell instead of just making a half-ass port of the 360 GPU-code. Oops there I said it.

That theory sounds a little out there... if the PS3 is downlclocked later to be bumped to 550MHz I expect the reasons would be more business related. For instance, Sony perhaps realizes that a smaller form factor and cheaper component cost could more easily be achieved at 500MHz GPU and 650 MHz RAM than that would be more beneficial in getting PS3's in peoples homes compared to a 10% bump in performance. Of course, if all PS3 shipped today are capable of handling 550MHz GPU and 700MHz speeds and Sony simply wanted to keep more options open to them and the hardware comes more or less at the same price then I guess they could bump up the performance.

I doubt if any of this is true though and am already enjoying my PS3 too much to care.

 

[Crossbar]

That theory sounds a little out there... if the PS3 is downlclocked later to be bumped to 550MHz I expect the reasons would be more business related.

Prolonging the life-cycle of the platform is pretty business related IMO.

The speed increase of the PSP together with the addition of some previously reserved memory (mentioned by some devs here) will certainly breath life in a new generation of games for the PSP. Developers are given resources that will help them make sequels of games that can really feature an improved look and feel, which will help motivate the consumers to buy the sequel.
Perhaps the PSP games were starting to stagnate after 3 years, perhaps Sony wanted to give the games a boost when the new model was released.

There may also be more than one cause for Sony to motivate their down-clock decisions, perhaps battery life on early PSP units was one, perhaps noise issues on early PS3 units was another one and perhaps both were in conjunction with life cycle considerations.

Distributing the game improvements evenly over the life cycle of the platform sounds like a pretty smart idea in my ears, the more you are in control of it, the longer you can stretch the life cycle. I am sure Microsoft, Nintendo and Sony partly achieve this through the regular updates of the SDKs and APIs that they make available to the developers.