Developer of OCCT 3.1 "HD4870/4890 Can't handle GPU Stress tests."

[Squall-Leonhart]

Who are you ?
I'm the guy behind the well-known program OCCT, which has recently become an all-rounder stability check program (CPU, GPU, Power supply). English is not my native language, so please excuse the mistakes

What's the point ?
Recently, i've been working alot on the RC1 version, and especially on the GPU:3D test. It has been improved dramatically, and this new test revealed a hardware design flaw in the new Radeon HD4870/4890 cards who followed the ATI/AMD reference design. Cards like PowerColor 4870PCS+ are NOT affected, as they are custom design.

They basically crash because they can't handle the load. Early testing shows the VRM cannot supply enough power to the card. That's the only thing i could dig until now, with limited testing means. They seem limited to 82/83A. Please help us dig more !

For a 3d developer, that means : "Do not optimize your code too much for ATI cards, or you could reach the limits, and crash them".

What's this test doing ?
The new test is still a furry donut, but it sports, among new features, a shader complexity parameter, which is, as its names states, how complex the shader will be, i.e. the amount how work the graphic card will have to do in one pass. The highest value is not always the best. For HD4XXX cards, 3 is the best value.

Let me stress the following points :

• This test uses DirectX9, which is updated SEPARATLY from DirectX 10 and 11. Install it from Microsoft Website
• I do NOT use other functions than DirectX's basic function. Really, nothing fancy. Shader Model 3 shaders, alot of Alpha blending... and that's it !

Is there a specific test configuration to reproduce it ?
Yes. First download OCCT by going on the official website and grabbing the RC1 : ocbase.com • View topic - OCCT PT 3.1.0.RC1 Available !

Next, the goal is simple : maximise the GPU load. Here is the way to do so on those cards. Be sure to use these settings !

• Enable Fullscreen Mode
• Disable Errorcheck Mode (comparing images is NOT effective)
• Use a High resolution. Preferably the native resolution of your screen (i.e. 1680x1050 for a 22" LCD, etc)
• Shader Complexity 3 for HD4XXX cards

Click "Go" and watch your screen go black. Your card has gone into protection mode. Frequencies dropped to 200Mhz. Reboot is needed.

How many cards are affected ?
Right now, we've successfully crashed about 10 different cards using this test, using alot of different power supplies (ranging from 550W Antec to 1500W ToughPower (!!!). We had Seasonic, Corsairs... etc).

OCCT 3.1.0 shows HD4870/4890 design flaw - they can't handle the new GPU test ! - XtremeSystems Forums