To your reference, this is my results with fglrx 10.10 beta in Ubuntu maverick.
This was benchmarked on a C2D 2.5 GHz, with HD4650.Code:Lightsmark: lightsmark [Resolution: 1920 x 1080] Test Run 1 of 1 Expected Trial Run Count: 3 Started Run 1 @ 15:47:48 Started Run 2 @ 15:49:52 Started Run 3 @ 15:51:54 Test Results: 54.92 55.48 54.99 Average: 55.13 Frames Per Second
3X between Win OpenGL and Mesa3D (gallium3D). A lot of Performance optimization is needed. Nonetheless, all Open Software effort is greatly appreciated.
I thought this thread was about R300-R500.
I regularly run very intensive OpenGL apps in windows on my ATI card with no issues. While it's certainly possible your benchmark app hits some particular driver path that isn't as stable as what my apps hit, the "runs fine for a bit, gets corrupted looking, crashes" is almost the textbook prime symptom of an over-heating GPU.