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OpenCL

himanshu_gautam
Grandmaster

Re: Using HD7970 as secondary GPU for OpenCL only

Hi darkman,

I will get back to you on this. Thanks for sharing the results.

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himanshu_gautam
Grandmaster

Re: Using HD7970 as secondary GPU for OpenCL only

Hi darkmen,

I am still not able to reproduce this issue at my end. I have not been able to test on tahiti (because of its availablity), but my HD7750 do not show any signs of this performance degradation.

Willl it be possible for you to send some steps as to what all you installed, and in what order.

Have you tried changing the BIOS settings of your machine. Try making iGPU as primary device adapter.

Also I think you have not installled any other OpenCL SDK(intel's ?) as you only want to use intel's GPU for display purpose?

Thanks for your patience.

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developer
Adept II

Re: Using HD7970 as secondary GPU for OpenCL only

Hi,

As a temporary workaround, can you try extending your desktop to the secondary GPU?

This can force the OS to increase the clock-speed in the secondary GPU.

If this works, we can just extend 1 scanline to the secondary GPU and get the required performance.

you will loose a pixel column for superior GPU performance.

Just a thought.

Best Regards,

Workitem 6

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darkmen
Journeyman III

Re: Using HD7970 as secondary GPU for OpenCL only

Hi, there is no primary card settings in BIOS (atleast in windows gui tool from Gigabyte), and there is no monitor hardware newr the PC to try normal way. As i wrote in my first post - both cards running w\o monitors connected.

MB has only HDMI output for video, so i tried to connect some tv instead of monitor.

Well, it still cant enter bios (black screen, seems tv not supports low res) but, in windows it works correct. And with tv plugged in iGPU, clinfo reports 1100 MHz for AMD. After I did reboot w\o tv it falls back to 500 MHz again.

So, technicaly i need to find HDMI dummy plug for iGPU as workaround (if it exists)

But, would be nice to have some software way for this issue.

THanks in advance

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darkmen
Journeyman III

Re: Using HD7970 as secondary GPU for OpenCL only

Unfortunatley this not works. When i press Extended desktop - nothing happens (reminding, none of GPUs have monitors connected, becuase this is a compute unit, not a work unit)

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himanshu_gautam
Grandmaster

Re: Using HD7970 as secondary GPU for OpenCL only

I am just curious here. If both your GPUs (integrated as well as discrete) are not connected, how are you extending the desktop? Are you using remote desktop to connect and work with this machine?

You have said that if a TV is connected to iGPU, AMD GPU shows correct clock speed (By iGPU - I assume you mean Integrated Intel GPU). Can you try connecting something to AMD GPU and check what clock speed is reported? - if this is not a hassle.

For a s/w workaruond -- will ask around if this is expected behaviour (or) if there is some work around for the same.

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himanshu_gautam
Grandmaster

Re: Using HD7970 as secondary GPU for OpenCL only

Hi,

I tried using my setup with out any monitors attached. I used windows RDP to access the machine remotely. As of now, I have not seen any degradation in tahiti clock. Can you explain your hardware setup, and how exactly are you accessing it.

Also can you please share the source, for the method used by you to select the primary video adapters.

AFAIK, you should select the primary video adapter from BIOS settings. (probably somewhere in advanced settings).

Message was edited by: Himanshu Gautam

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darkmen
Journeyman III

Re: Using HD7970 as secondary GPU for OpenCL only

Hi, from the start I want to say:

I used TeamViewer for remote access to display-less workstation before.

Today I have tried RDP and had different experience:

1. OpenCL application shows correct core freq and running full speed using RDP. System feedbacks good even for long kernel execution time (like a few seconds+)

2. Screen settings are a bit different under RDP because it uses own display/driver

But anyway, CCC not even starts under RDP and this way overclocking options are not available. May be this is because of missing phisical display (not sure)

Closing current question as answered, but would be good to know what was wrong for TeamViewr (i belive VNC will be the same too)

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nou
Exemplar

Re: Using HD7970 as secondary GPU for OpenCL only

there is difference between RDP and VNC/TeamViewer. RDP is using virtual graphic card but VNC is using actual physical GPU. This was problem in the past as there was no access to GPU with OpenCL under RDP.

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darkmen
Journeyman III

Re: Using HD7970 as secondary GPU for OpenCL only

Well, not in the past. Its not possible to set core/mem clock for AMD GPU under RDP session currently, because CCC not even starts, and 3rd party tools (those i belive use AMD API) cant get fan/temp data and set freq.

BTW,  AMD System Monitor screenshot is the same as in my first post (no GPU usage or MHz data)

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