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I have a Sapphire Vapor-X Radeon HD7950 OC edition graphics card. It runs at 850 MHz using the regular BIOS and at 950 MHz using the Boost BIOS.

I'm using the Boost BIOS. When computer boots, the card runs at 950 MHz when under load, as expected. I then use Trixx to overclock GPU from 950 to 1150 and memory from 1250 to 1400, using a +20 power setting to make it stable. It runs well, can run tests and games for hours, doesn't overheat, has no artifacts.

However, when I launch any GPU-accelerated video player, such as VLC or SMPlayer, frequency immediately drops to 850 (not 950!) and memory drops back to 1250. It stays there as long as the video player is opened, even if it paused. When I close it, I have to reset the overclock in Trixx and do it again to get back to 1150/1400.

Disabling 3D acceleration in the video player makes the problem go away but then the player is obviously a lot less usable. I need the overclock to run modern games, the difference is crucial for achieving good FPS in current games.

What is the reason for this behaviour? Can it be altered so that my video players would be properly accelerated and would not affect my overclock?

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    One of my GPUs is the Dual-X OC 7950, when I get home I will check if this happens for me too, I have never noticed something like that before. – user438322 Apr 23 '15 at 19:13
  • I've accidentally discovered that running the game in windowed mode doesn't affect clock. I can run both the game and a video at the same time at 1150 MHz. That makes the situation a bit more bearable. – Jurij Apr 25 '15 at 20:22
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This is because GPUs tend to have 2D and 3D modes. Normally opening DX(games) will kick the GPU up from idle/2D into 3D mode chaning from min clocks to max clocks. But when you open a video player its seeing a 2D application and applying those clocks despite the already running 3D application.

Listing your video player as a "game" like here should hopefully resolve it. This link is close to waht you need to do (its not Optima here). How to force my laptop to use the discrete GPU?

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  • Thanks for this. Unfortunately, adding the player under Games/3D Apps section has no effect. VLC is tricky, it seem to operate in a kind of "low level" way and nothing I set in GPU controls has any effect. – Jurij Sep 29 '15 at 14:51

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