Graphic Cards Geforce 7800GTX clock speed blunders.

Shripad

Shripad

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I was discussing something with Unwinder today (Rivatuner programmer) as he has had a lot of reports of unusual core clocks for the GeForce 7800 GTX. After investigating it myself it seems that the minute you startup a 3D application, the GPU core frequency jumps towards 468 MHz (should be 430), a ~40 MHz difference is reported with any GeForce 7800 GTX. You can only measure this once you actually follow the clock real-time (see image below).

I just verified it, during some new test sessions with core clock monitoring we noticed that the G70 although clocked at 430 standard will in 3D applications immediately jump towards 468 MHz. Even overclocked at 480 Mhz the clock will jump towards 522 MHz, again that ~40 MHz difference. What is going on in that G70 GPU huh ??

After puzzling this and actually noticing that ASUS even has a marketing phrase for this called "geometric clock delta", they are actually advertising a 470 MHz product under that name with 'geometric clock delta' advertised.

As it looks right now, we will have to drop the idea of 2 frequency clocks on the G70 card (core/memory). What is going on with that 40 MHz differential ? We currently think that the Pixel and Vertex pipes or triangle setup might be clocked differently to explain that differential. Or even Shader Clock 430 MHz/Rop Clock:430MHz/Geometry Clock:470MHz.

We're not sure, but this is really interesting ! I fired off emails towards NVIDIA and hopefully I can get you a more detailed answer soon.

Update 1:

Answer from NVIDIA:

Hey Hilbert,

As our chips become more advanced, we are implementing more complex clocking inside the chip. 430MHz is the primary clock speed of the chip and can be verified by fill rate tests.

We will work with Rivatuner to read the correct registers in order to report the right clock.

Hope this makes sense.

Now if you disect that answer (as vague as it honestly is) we can make note of the fact that NVIDIA uses "Primary" clock speed. Obviously, there's a secondary clockspeed running also. Very likely there are surely different clocks for different pipes.

If 430 remains the primary clock then why can Asus (check that here) advertise it as 470 ?

That would be somewhat misleading to you, the consumer as you think it's an uber Ultra version or something like that. They sincerely use this to advertise:

Engine Clock 470 MHz**
**NV clock(430MHz)+Geometric Delta clock(40MHz)

As it seems nobody can explain the 40 MHz differential properly, yet is is being used as marketing gimmick, consumers automatically assume it's 470 MHz where that's not 100% true.
Click to expand...

Source : http://www.guru3d.com/newsitem.php?id=2827
 
an update.
Well this has been an interesting development for sure. A couple of days ago we already reported that we noticed strange core clock behavior on GeForce 7800 GTX graphics cards. Basically the primary clock of the GeForce 7800 GTX in 3D mode should always be 430 MHz (unless you overclock or put the card in Dynamic mode).

Rivatuner and software like the 3DMark suite are both reporting that what is supposed to be 430 MHz clock speed of the G70 core to be 468 MHz. Initially I figured this to be a bug and simply ignored it. However, a week after Rivatuner 2.0 RC15.6 was released Alexey (Rivatuner) contacted me regarding some ASUS advertising and asked if I knew anything about something that is called the Geometric Delta Clock. We chatted and theorized a little whether what exactly this phenomenon was. Well, read the previous bulletin to be informed properly I guess.

Now then. Even if you overclock your GeForce 7800 GTX towards 500 MHz the actual realtime monitoring results would show back 540 MHz, again that 40 MHz difference. Then we stumbled into some more advertising from ASUS. They where advertising the product to be 470 MHz everywhere, yet when you dig into the specifications deeply you'll notice this line "NV clock(430MHz)+Geometric Delta clock(40MHz)".

And that made us both wonder very much. I've been chatting with manufacturers and of course also tried to get a comment from NVIDIA. Ehm, suffice to say that NVIDIA at this point will not comment (they are protecting the new gimmick, so that makes perfect sense, do not blame them for that). The new technology that we found by accident is in fact simply a new innovation, not a weird cheat or something like that.

During our efforts in asking around, trying to get official comments and what not Alex has been working on various monitoring options and we know for sure that it is not a bug. The GeForce 7800 GTX is making use of three different clocks, period. After examination from Alexey we can say for sure that the Geometric clock delta, as ASUS called it, is explicitly specified in the G70 VGA BIOS for each performance level.

When dumping the VGA BIOS info into Rivatuner it will display both ROP and ROP+delta (geometric) clocks. For those that want to know. ROP is short for Raster Operation and a portion of a pipeline, responsible for AA, Blending and Z-Buffer compression. A ROP is basically the output engine of a pixel shader pipeline.

Right now a new Rivatuner Beta is in the works that will allow you to monitor and display the three clocks. So expect some cool new diagnostic enhancements in the upcoming Rivatuner release. Unfortunately for you .. this new RT is being released next month.

Now then what's the point of all this, ehm to satisfy our curiousity ? NVIDIA has integrated a new technology that they will not discuss at this time while we know it's there. More info will be posted once we find new stuff or when NVIDIA chooses to make a formal comment on this.

Bare in mind though that (and this does come from NVIDIA) the primary clock for any GeForce 7800 GTX product remains 430 MHz even if a manufacturer like ASUS uses 470 MHz in it's press-releases and their e-tail channels, for an example have a look here.
Click to expand...

source:http://www.guru3d.com/newsitem.php?id=2836
 
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