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Built on a .25 micron process, TNT2 naturally can be clocked higher than the .35 micron TNT. The 'ultra' version of TNT2 has a default clock of 150 MHz, or 300 megatexels per second. Even with active cooling, it was erratic at 170 MHz. The effect of changing core clockspeed, and hence potential fillrate, is illustrated with 'Expendable', 'Unreal' and 'Quake2'.
The graphs depict 16-bit rendering at 1024x768 with varying core clocks and CPU speeds. Memory clock was maintained at 200 MHz throughout to provide maximum bandwidth.
Expendable
Unreal
'Unreal' and 'Expendable' are entirely limited by the CPU at speeds of 300 and 338 MHz. At 450 MHz, 'Unreal' framerates are more responsive to core clock increase as compared to 'Expendable':
| 'Unreal' framerates |
| 32.2 fps at
110 MHz core |
| 35.9 fps at
170 MHz core |
| |
| 'Expendable' framerates |
| 33.6 fps at
110 MHz core |
| 35.9 fps at
170 MHz core |
This would suggest a higher fillrate requirement on the part of 'Unreal'. The extent to which fillrate is soaked up depends on depth complexity, overdraw and number of rendering passes. At 450 MHz, the curves of both games are on the verge of reaching a plateau. A higher speed CPU would probably shift the bottleneck to the accelerator.
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