Please Clear This Up - What PC GPU Does the XBOX 360 & PS3 Use?

[JarHead]

Hey Guys,
I haven't posted here in a LONG time, but I knew if there was a place to find this answer - it would be here. I know that the GPUs in the Xbox 360 and PS3 don't have a direct PC counterpart, but can someone tell me which PC GPU is the closest match?

I've searched all over the place, but there seems to be some differing opinions.
I've read some places say the 360 GPU is comparable to a X1900XT + the 10MB embedded ram makes it better. However, I've read some places that the 360 GPU is no better than a 7800GT (I don't know why they used that comparison since the 360 uses an ATI GPU).
As for the PS3, weren't saying that it would outperform 2 7800GTs in SLI (or was it 2 6800GTs)? I also remember reading here that it would be similar to a 7600GT (because of the 128bit mem).

Can someone clear this up for me in one short and sweet answer?
Thanks

 

[ERP]

Short answer is that their is no equivalent PC GPU, or one that's even remotly close.
Architecturally the X360 GPU is radically different than anything on the PC side.
There are some similarities between the ALU's in PC ATI parts and X360's GPU, but they are used in different ways.

 

[sonyps35]

Yeah the ATI comparison with Xenos is a tough one.

RSX though by all evidence is a 7900GT clocked at 550 mhz core. More or less that's it's internals. It's a 24 pipe G71 part clocked at 550 mhz, whatever you want to call that since 7900GT/X's have so many different clocks depending on vendor..Yes it's also going to have a 128 bit bus, perhaps with a little help from the flex/io bus. So it's best classed as a 550mhz 7900GT/X with a 128-bit memory bus.

You can thumbnail the Xenos roughly by ALU's. 48 ALU's, two make a pixel pipe and one makes a vertex pipe in PC GPU's. So if you break off 8 for vertex pipes in Xenos you're left with 40, or 20 pipes. So it could be a 20 pipe-500 mhz ATI card equivilant, with various caveats like EDRAM, the fact the second ALU per pipe is madd capable whereas on ATI PC parts it is not, etc.

This is all very rough and innacurate..it seems clear Xenos is a mid-upper range PC GPU from the game comparisons we have now though.

 

[JarHead]

Thanks for the quick reply
Well, I had thought that based on the clock/mem speeds, pipelines, etc that it should be close to a X1900XT (and others have said that). However, keep in mind that while I may be considered, in my circles, to be a computer geek just because I can throw specs around, but when it comes right down to it - I often get lost in the Tech discussions that go on around here. Also, that comment I read on another forum that it was no better than a 7800GT threw me off (and no one else contested the statement).

 

[JarHead]

Yeah the ATI comparison with Xenos is a tough one.

RSX though by all evidence is a 7900GT clocked at 550 mhz core. More or less that's it's internals. It's a 24 pipe G71 part clocked at 550 mhz, whatever you want to call that since 7900GT/X's have so many different clocks depending on vendor..

Hmm, what about the 128bit mem?
Also, I thought it was a 12 pipe card.

 

[sonyps35]

Hmm, what about the 128bit mem?
Also, I thought it was a 12 pipe card.

Nope it's 24 pipes. With a 128 bit bus. There's not an exact PC comparison. But it's basically a 7900GTX with a 128 bit bus.

I read on another forum that it was no better than a 7800GT threw me off (and no one else contested the statement).

Probably a fanboi just like the one who stated RSX is just like a 7600GT. Fanboi's will state all kinds of deragotory things against the "other guy". Perhaps even with a sliver of truth involved but not the whole picture.

Although, Xenos is probably not a great deal more powerful than a 7800GT. For that matter neither would RSX be.

Both would be classed as mid-upper range PC-GPU's..which a 7800GT is pretty close to that anyway..

 

[JarHead]

Roger that! Thanks Sony.

 

[Acert93]

Hmm, what about the 128bit mem?
Also, I thought it was a 12 pipe card.

Lets not use the term pipes It was useful in the past because each Pixel Shader had a TMU had a ROP. So a GPU like the 9800Pro had 8 Pixel Shaders, 8 TMUs, and 8 ROPs. With RSX it is not that easy. Is it a 8 pipe part because it has 8 ROPs? Or is it a 24 pipe part because it has 24 Pixel Shaders and TMUs?

RSX has 24 Pixel Shaders. They are basically the same as the Pixel Shaders in RSX (48 MAD/MUL/DP3 per clock on float3's and 48 scalar per clock (or 24 and 24 special functions)). RSX also has 24 texture units. It appears to have 8 ROPs like the 7600GT instead of the 16 ROPs on the G70/G71 GPUs. There are also some cache changes. On the memory side RSX has access to 256MB of GDDR3 @ 700MHz over a 128bit bus (22.4GB/s). This is similar to the 7600GT, but the difference being is that RSX can also access XDR through the FlexIO as well. Cell also can write to RSX through FlexIO and can also write to the GDDR3 at ~4GB/s.

Basically RSX is derived from NV's G70 technology with some tweaking to fit withing the PS3 environment. Which agrees with what NV/Sony had stated would happen when they first announced the deal back in Dec 04/Jan 05 (whenever it was).

And as ERP said, Xenos is quite distinct from ATI's current desktop line. It has some similarities, but utilization and workflow are different in some key areas.

 

[Megadrive1988]

RSX though by all evidence is a 7900GT clocked at 550 mhz core. More or less that's it's internals. It's a 24 pipe G71 part clocked at 550 mhz, whatever you want to call that since 7900GT/X's have so many different clocks depending on vendor..Yes it's also going to have a 128 bit bus, perhaps with a little help from the flex/io bus. So it's best classed as a 550mhz 7900GT/X with a 128-bit memory bus.

minus 8 ROPs, thus minus half the pixel fillrate per clockcycle. plus whatever else may have changed. even though RSX does apparnetly have 24 pixel shader units. so no, RSX is not a 7900GT/X nor is it a 7600GT either.

RSX has 8 pixel pipelines, not 16, and not 24. (not even the G71 has 24 pixel pipelines, it has 16)

 

[JarHead]

Lets not use the term pipes It was useful in the past because each Pixel Shader had a TMU had a ROP. So a GPU like the 9800Pro had 8 Pixel Shaders, 8 TMUs, and 8 ROPs. With RSX it is not that easy. Is it a 8 pipe part because it has 8 ROPs? Or is it a 24 pipe part because it has 24 Pixel Shaders and TMUs?

RSX has 24 Pixel Shaders. They are basically the same as the Pixel Shaders in RSX (48 MAD/MUL/DP3 per clock on float3's and 48 scalar per clock (or 24 and 24 special functions)). RSX also has 24 texture units. It appears to have 8 ROPs like the 7600GT instead of the 16 ROPs on the G70/G71 GPUs. There are also some cache changes. On the memory side RSX has access to 256MB of GDDR3 @ 700MHz over a 128bit bus (22.4GB/s). This is similar to the 7600GT, but the difference being is that RSX can also access XDR through the FlexIO as well. Cell also can write to RSX through FlexIO and can also write to the GDDR3 at ~4GB/s.

Basically RSX is derived from NV's G70 technology with some tweaking to fit withing the PS3 environment. Which agrees with what NV/Sony had stated would happen when they first announced the deal back in Dec 04/Jan 05 (whenever it was).

And as ERP said, Xenos is quite distinct from ATI's current desktop line. It has some similarities, but utilization and workflow are different in some key areas.

Excellent break down. I was just looking at gpureview and comparing all the different "pipes" of the 7600gt & the 7900gt.

 

[sonyps35]

minus 8 ROPs, thus minus half the pixel fillrate per clockcycle. plus whatever else may have changed. even though RSX does apparnetly have 24 pixel shader units. so no, RSX is not a 7900GT/X nor is it a 7600GT either

Perhaps that's why I used terms like "basically" or "best classed"

To call the RSX 8 pipelines is irrelevant from a performance point of view, so why use such terminology?

I called it "24 pipes" and that will give a much more accurate idea of it's performance than 8 pipes will. I understand the desire to shift from pipeline terminology, when it makes sense, but then why use less informative terms instead?

If it's 8 of something that's irrelevant more or less..there's no need to mention that at all. The fact it is qoute un qoute "8 pixel pipes" tells me nothing about it's performance.

 

[Acert93]

If it's 8 of something that's irrelevant more or less..there's no need to mention that at all. The fact it is qoute un qoute "8 pixel pipes" tells me nothing about it's performance.

Neither does calling it 24 pipe.

e.g. ROPs and Pixel Shaders have better performance per clock in the GF7 series compared to the GF6. So a GF6 16 "pipe" part is not necessarily comparable to a GF7 16 "pipe" part to begin with. Architecture makes a big difference--especially when comparing IHVs.

Second, how many "pipes" is the X1900? 48 Pixel Shaders, 16 TMUs, and 16 ROPs.

Are you going to tell me it is a 16 "pipe" part? Benchmarks are a big negative there. What about a 48 "pipe"? Nope there either.

Third, what is Xenos? 48 Shader ALUs, 16 TMUs, and 8 ROPs.

48 pipe?
16 pipe?
8 pipe?

Talking about "pipelines" was relevant back around the R300 days, but it just does not apply anymore. Graphic demands have changed and continue to change. Bottlenecks are not what they were.

I guess if you wanted to say Xenos performs like a 48 Shader "pipe" part in Shader limited scenarios, 16 "pipe" part in texture limited scenarios (ignoring it has more robust and decoupled texture units), and 8 "pipe" part in purely fillrate limited scenarios.

But then again this ignores featureset (features can often do the same end result at a fraction of the performance; e.g FP10) and the shader model and how well it performs such.

Really, 24 "pipe" doesn't tell us much about its architecture, how it performs to various products outside its immediate series (and even that is iffy), nor its implimentation and featureset -- i.e. how it is used. Based on the GPUs released in the last 12 months where the rendering pipeline has either become fully or partially decoupled, pipeline is not really relevant anymore. It is an antiquated term and doesn't tell us much about performance.

 

[Megadrive1988]

by glancing over Acert93's post, I'd say he's most certainly just about correct, if not completely so.


Xenos is not at all comparable to anything else in the ATI families of PC GPUs.


RSX is at least somewhat comparable to other Nvidia GPUs in the NV47 ~ G7x family. we'll see soon enough just what RSX is.


.....and in some years time, the current terminology we use for GPUs will be outdated once again

 

[sonyps35]

Neither does calling it 24 pipe.

Actually yes it does Especially with Nvidia parts which still scale precisely according to pixel shader pipeline count.

But we're going way OT now..although that's the fun part anyway

 

[TurnDragoZeroV2G]

You can thumbnail the Xenos roughly by ALU's. 48 ALU's, two make a pixel pipe and one makes a vertex pipe in PC GPU's. So if you break off 8 for vertex pipes in Xenos you're left with 40, or 20 pipes. So it could be a 20 pipe-500 mhz ATI card equivilant, with various caveats like EDRAM, the fact the second ALU per pipe is madd capable whereas on ATI PC parts it is not, etc.

This is all very rough and innacurate..it seems clear Xenos is a mid-upper range PC GPU from the game comparisons we have now though.

Not just no MADD, no MUL. They're also only 4-wide, whereas Xenos' units are 5-wide. Really, two such ALUs aren't even roughly comparable to one shader unit from the R5xx series (where X1900 has 4x4x3 such 'shader units').

Michael Dogget has already said Xenos' shader power exceeds that of an X1800 in such a use as that of running the Toyshop demo. So, very innaccurate, as you said, when you come to 20 pipes at 500MHz vs >24 "pipes" at 625MHz.

Pipes... they're bad, so we should all stay away from them.

 

[sonyps35]

Actually Doggett said X1800 and Xenos were comparable in shader power.

And pipes are still a very good term IMO. In fact the best single shorthand term to describe cards performance. With caveats of course.

And you miss that X1800 is 16 pipes..so at 625..yeah comparable to 20 pipe 500 mhz hypothetical Xenos..according to the designer Micheal Doggett

But I'm not really arguing pipes are valid when discussing XENOS anyway..never said that. Although we'll just switch to ALU's as the base unit instead..

 

[TurnDragoZeroV2G]

Right, my mess up there.

Nevertheless, the words used in that comparison were "(slightly) more", not "comparable," which definitely places one above the other, rather than some vague "close, one way or another."

 

[LunchBox]

Hey Guys,
I haven't posted here in a LONG time, but I knew if there was a place to find this answer - it would be here. I know that the GPUs in the Xbox 360 and PS3 don't have a direct PC counterpart, but can someone tell me which PC GPU is the closest match?

I've searched all over the place, but there seems to be some differing opinions.
I've read some places say the 360 GPU is comparable to a X1900XT + the 10MB embedded ram makes it better. However, I've read some places that the 360 GPU is no better than a 7800GT (I don't know why they used that comparison since the 360 uses an ATI GPU).
As for the PS3, weren't saying that it would outperform 2 7800GTs in SLI (or was it 2 6800GTs)? I also remember reading here that it would be similar to a 7600GT (because of the 128bit mem).

Can someone clear this up for me in one short and sweet answer?
Thanks

AFAIK
Xenos is a X1900



(+) plus

10 MB EDRAM (32GB/s connection to GPU, internal 256GB/sec)
free AA upto 4x (???)
10-bit HDR and AA
48 ALU/Unified shaders
some possible shader capabilities not available to the X1900
UMA negating any DATA copying/replication


(-) minus

8 ROPS
128 bit bus
22.4 GB/s unified bandwidth to be shared with Xenos
no vertex shaders (opposed to 8 vertex shaders in addition to the 48 fragment pixel shaders(2 ALU+1BEU each fragment pixel shaders) that is available to the X1900)
simpler ALU configuration as opposed to the X1900
some shader abilities on X1900 not available to Xenos



Still no sign of any technical article to properly determine RSX aside from it being a 7800GTX minus 8 ROPS, 128-bit bus and possible quads being disabled for redundancy...

please feel free to correct me if I am wrong

 

[Dave Baumann]

Xenos is not at all comparable to anything else in the ATI families of PC GPUs.

Yeah it is. They just aren't available yet...

 

[sonyps35]

Yeah it is. They just aren't available yet...

Heh..it'll be awesome to get a comparitive PC side GPU benchmarked..

Assuming that ever happens..main problem I see is if ATI retains the PC mini-ALU for R600 we'll never get a clear comparison.