BP=0 and how it relates to locked frame rate.

With my old system, i7920 at 4GHz, GTX580, I could run BP=0 without any issues. In fact I gained a rather nice 10 frames per second boost. However, when I upgraded to Ivy bridge, i73770k at 4.5 GHz, still with my old GTX 580, I found BP=0 generated artifacts. Therefore I was forced to use a reject threshold instead.

Finally got round to a few tests the other day, and the solution was very simple.

I usually run with the FSX frame lock at 60. Yes, some will say it should be lower, but for me, locked at 60 has always worked very well, rarely any stutters and no artifacts. In GPUz, GPU usage was at 77% with the frame rate locked at 60.

I simply knocked the frame rate lock back to 50 and all artifacts were gone. In addition, GPU usage dropped to 64%.

So now I can run with BP=0 without issues.

Frame rate in the NGX cockpit, on the runway at EGLL, grey an rainy weather scenario, was about 27. Now... 44 FPS. 15 frames higher. A full 63% increase in performance. You can imagine how pleased I am that I now have BP=0 working again.

So the question for the BUFFERPOOLS experts is... why was BP=0 and locked at 60 FPS fine with an i7920/GTX580 at 4GHz, but not with an i73770k/GTX580 at 4.5GHz?

Why would a more powerful CPU result in graphical artifacts and require a slight reduction in frame rate lock? Something to do with the CPU GPU balance perhaps?

My theory is that the more powerful CPU, was simply pumping too much at the graphics card, too much for it to handle. And by limiting frame rate slightly more, there was less strain on the GPU, clearing up the artifacts.