Is the PS3 on track to deliver full specs?

[SPM]

Don't forget the PS3 is supposedly a lot quieter than XBox360, and since Sony is aiming the PS3 as a BD player as well, it will need to be quiet. If Sony is looking to downclock the PS3 then this is the likely reason why.

 

[nAo]

A 650 Mhz GDDR frequency (instead of 700 Mhz) would mean a 7% reduction on local bandwidth and a 2.5% reduction on total RSX bandwidth.

 

[Laa-Yosh]

But as to the 'meat' of his post, there has been talk of 500/650 on the RSX, and this comes from sources better than the Inq's I can assure you. But at the same time, 'specs are subject to change,' so you know the deal...

I have also heard about the clockspeed downgrade, from a reliable source, several weeks ago...

 

[V3]

A 650 Mhz GDDR frequency (instead of 700 Mhz) would mean a 7% reduction on local bandwidth and a 2.5% reduction on total RSX bandwidth.

For HD with AA, isn't RSX bandwidth starve to begin with ? Or is it more shaders limited ?

If they choose to reduce the RSX instead of Cell to fit their thermal envelope, does that mean PS3 is more Cell limited ?

 

[Jesus2006]

A 650 Mhz GDDR frequency (instead of 700 Mhz) would mean a 7% reduction on local bandwidth and a 2.5% reduction on total RSX bandwidth.

That "would" seems like a negative confirmation to me

I have also heard about the clockspeed downgrade, from a reliable source, several weeks ago...

Yeah, and we heard the same things a year ago before the 360 launched, like going down from 3.2Ghz -> 3.0Ghz...

 

[nAo]

Sometimes being smart instead of using brute force can do magic: with MSAA compression (color and z) can really save tons and tons of bandwidth at the point that AA becomes almost a no brainer (as long as you can afford enough memory to store you MSAAed frame buffers..)

 

[cau]

Isn't it safe to say that RSX is not your run of the mill G70 now that they have problem to get it up to 550 Mhz? A G80 at 500 Mhz would not be bad.

 

[Fafalada]

For HD with AA, isn't RSX bandwidth starve to begin with ?

That's quite alright, if you look at nAo's post again(very closely), you will notice that relative ROP bandwith would actually increase by 1.3% in 500/650 configuration.

 

[inefficient]

Isn't it safe to say that RSX is not your run of the mill G70 now that they have problem to get it up to 550 Mhz? A G80 at 500 Mhz would not be bad.

I certainly hope so. Having to drop the memory and core clock on a part that is supposed already tried & proven would seem to be a pretty major execution failure.

Fingers crossed.

 

[aaaaa00]

That was a leaked document. An internal schematic with rough placeholder figures (this is also the document that specifies "256MB+" for the RAM, which was indeed originally intended at 256M

Indeed.

Ignoring the fact that this was a leaked document, and not an announcement... 512 MB of system memory was probably the single most important and effective upgrade MS could have put into the 360 described there. Doubling system memory was an upgrade that will cost them an extra 900 million dollars over the lifetime of the 360, and also contributed to the unit shortages they had at launch. [1]

IMHO, this upgrade outweighs any CPU downgrade of a few hundred MHZ by a huge factor, and is one of the key choices that allows the 360 to be competitive with a console coming out an entire year after it.

---

[1] see Dean Takahashi's book, page 280 and 345

 

[Titanio]

Isn't it safe to say that RSX is not your run of the mill G70 now that they have problem to get it up to 550 Mhz?

I certainly hope so. Having to drop the memory and core clock on a part that is supposed already tried & proven would seem to be a pretty major execution failure.

It does seem disappointing given the clocks you see in the PC space, but there are constraints in place here that don't exist in a PC. I doubt it's a matter of not being able to get the yields up at that clock*, but being able to do so within given constraints, which are likely much tighter than for a chip going into a PC, as already mentioned by others (heat, power, noise etc.).

*I presume it cannot be any more difficult to manufacture a certain number of 550Mhz RSXs per month than a 3.2Ghz Cell, although I guess their sources for the former may not be as numerous as the latter.

 

[MasterDisaster]

A 650 Mhz GDDR frequency (instead of 700 Mhz) would mean a 7% reduction on local bandwidth and a 2.5% reduction on total RSX bandwidth.

so we have an hit of 7.7 % on local bandwidth (texture stream and frame buffer), but we have another hit, 550 to 500 Mhz is an additional 9.1 % hit over all the gpu functions, vertex and pixel

is this right, nAo?

I remember that your HDR is using pixel ops to convert spaces from and to RGB, is this cost hitted by the -9.1 % performances of the gpu? how about the -7.7 % of the gddr3 bandwitdh?

 

[Jesus2006]

Ignoring the fact that this was a leaked document, and not an announcement... 512 MB of system memory was probably the single most important and effective upgrade MS could have put into the 360 described there. Doubling system memory was an upgrade that will cost them an extra 900 million dollars over the lifetime of the 360, and also contributed to the unit shortages they had at launch. [1]

You forgot that they had to do it, because Sony had it already and they would have lost badly if they didn't...

 

[MasterDisaster]

You forgot that they had to do it, because Sony had it already and they would have lost badly if they didn't...

I remember clearly that microsoft added 512 Mb to specs reacting to a petition from developers, not to a ps3 announcement
at the time ps3 specs was in the fog

 

[Sonic]

MasterDisaster, i'm sure a developer like nAo would have known about this some time in advance before it leaked here that a speed downgrade was going to occur. So with that they should be able to work around it a slong as they were given ample notice.

 

[mckmas8808]

Sometimes being smart instead of using brute force can do magic: with MSAA compression (color and z) can really save tons and tons of bandwidth at the point that AA becomes almost a no brainer (as long as you can afford enough memory to store you MSAAed frame buffers..)

Serious question nAo. Why aren't other developers as smart as you? I swear the AA that you guys have is outstanding. And you actually post how you do it on the internet. Why can't any general PS3 programmer just read what you wrote and put it in their game?

 

[Rash']

The Cell is at 3.2GHz and the RSX is at 500MHz. What are you not understanding?

Hang on with these figures the PS3 is identical to 360. How true is that in terms of performance?

 

[Jawed]

Another possibility is that RSX is base on G70 rather than G71. So the tuning and the trimming NV did to G71 from G70, is not done to RSX. This is a possibility considering PS3 was going to launch last Spring initially. And like Cell, its possible that RSX is already in production sometime ago.

I think this is very likely. I think RSXs (running at 420MHz) have been around since November though I'm sketchy on that. I'm reasonably sure that they were around before Christmas though.

Jawed

 

[_xxx_]

Hang on with these figures the PS3 is identical to 360. How true is that in terms of performance?

Not comparable since the architecture is different.

 

[Shifty Geezer]

Hang on with these figures the PS3 is identical to 360. How true is that in terms of performance?

No-one really knows. They're fundamentally different architectures. The fact the clockspeeds are the same is no indicator of the same performance from very different processors. Cell and XeCPU are both 3.2 GHz, but one is a tri-core, semi-conventional processor, and the other is an 8 core wierd thing. Both GPUs may be 500 MHz but one is a conventional 'fixed-function pipeline' device and the other is a new Unified Architecture.