   Missing triangles only on Geforce 7900 cards
  Hello,I'm having a problem with missing triangles when rendering models with a few thousand triangles. Models with lesser triangles are rendered properly.I'm using MDX 1.1 and DirectX 9.0c.I have tested my code on two PCs with Geforce 7900 cards. I have missing triangles on these configurations (both Windows Vista), some are missing constantly, others are flickering every frame. The number of missing triangles is relatively low, about 10-20 but very annoying.On every other card I tested all triangles are renderd properly (e.g. Radeon 9600, Geforce 6600, Geforce 4 and others).DX debug runtime output shows no noticeable problems.The problem disappears if I switch to software vertex processing.I have one other problem, maybe it's connected: On some cards I have no depth buffer when using pure device. The depth buffer is created but seems not to be used or cleared. The geometry is just showing through, no errors reported in debug output.But with only hardware vertex processing (without pure device bit) or software vertex processing or when using the debug runtime everything works.I hope someone can give me a hint, I already tried to reduce and narrow the problem with different models, different shaders and so on.I discovered that the problem only disappears with a very simple vertex shader and if I don't use normals in the vertex shader, the pixel shader seems to have no influence on the problem.Daniel   
  The two things you should try that you've not mentioned:1. Reference rasterizer. This will tell you if it's your code or the hardware that is wrong. Just because you get the correct results on other hardware doesn't mean you code is correct - it's not uncommon for some drivers to "massage" bad software and generate correct results.2. PIX for Windows trace. It can be slow work, but grab a single frame capture and step through every part of it. You should be able to tell if you've got broken depth/stencil tests as well as what the post-VS output is (etc..etc..)I've got a feeling that the missing triangles are going to be representative of something else - quite possibly a capability that you're assuming exists but doesn't on the 7900's. Your mention of lack of depth buffer with a pure device sounds like this, where you might be hiding some error with an incorrect depth format or so on...What enumeration code have you got in place?hthJack   