Noise, Overclocking and 2D Quality
The cooling system of the GeForce 7800 GTX 512 proved to be almost silent. You could only hear a soft rumble of the fan when your ear was not more than 10-15cm away from the operating testbed. Since the fan initially has a low speed, its speed management system is set up for the maximum in all the three modes: 2D, Low Power 3D and Performance 3D. We do not recommend you to tinker with these settings since the card is silent as it is, while your reducing the fan speed may put it under the risk of overheat. We want to note that the heat pipes and the heatsinks would become very hot after long operation, so additional ventilation in your system case would be most welcome, even though the cooling system borrowed from the Quadro FX 4500 handles the new NVIDIA card quite successfully without extra help.
Our overclocking experiments agree with our supposition that NVIDIA has created a new revision of the G70 chip capable of working at increased frequencies. Without using additional air cooling, we managed to overclock the GPU of our sample of the card to 600MHz. This is a mere 25MHz below the GPU frequency of the RADEON X1800 XT 512MB, but do not forget that the latter is a 0.09-micron chip and has only 16 pixel pipelines against the G70 Ultra’s 24. The memory reached its rated frequency, 900 (1800) MHz, and refused to overclock any further. The frequency potential of 1.1ns chips is probably exhausted and they cannot speed up any more at their default voltage.
The results of stepped overclocking tests were quite ambiguous. As we know, the regular GeForce 7800 GTX can be overclocked with 27MHz increment for pixel processors and if the increment is lower than this value, then there will hardly be any performance gain at all. The situation with the new NVIDIA graphics accelerator is completely different: it seems to have no overclocking discontinuity or to support any other overclocking increments than the 27MHz one. We overclocked the GeForce 7800 GTX 512 graphics processor from 550MHz to 595MHz with 9MHz increment and measured the results with Xbitmark tool and Marko Dolenc’s Fillrate Tester on each stage. Here are the obtained results: