Noise and Overclocking
The Gigabyte GV-NX76T256D-RH comes with a passive cooling system which is absolutely silent at work. A computer with that card installed would produce noise with an intensity of 40dBA, i.e. exactly with the same intensity as with any other passively cooled graphics card.
As usual, we tried to overclock the tested product. The card being equipped with a passive cooler, we put an additional 120mm fan to blow across the card’s PCB. We at first reached 680/800 (1600) MHz frequencies, but the system hung up after a couple of minutes in 3DMark06. The card was somewhat more stable at a memory frequency of 780 (1560) MHz, but again we had problems after a while. At 660/780 (1560) MHz frequencies the card was working normally for an hour, yet proved to be unstable in the end. So, the highest frequencies the graphics card was stable at, i.e. passed the full cycle of tests without ever showing image artifacts, were 660MHz GPU and 760 (1520) MHz memory.
When we were overclocking GeForce 7600 GT cards with the reference design we couldn’t notch even 600MHz, so the 100MHz GPU frequency gain we managed to get from the Gigabyte GV-NX76T256D-RH is an excellent result especially as we didn’t resort to extreme overclocking methods, modifications, etc. We’d like to warn overclockers against thinking that Gigabyte’s design suits better for overclocking than Nvidia’s reference design. The result we achieved doesn’t mean that the PCB developed by Gigabyte improves the overclockability of the GeForce 7600 GT because we tested only one sample of the card. More tests are necessary to collect statistical data and claim that one PCB design is better than another. We don’t have such statistics and don’t have time to gather it, so we are not sure that each sample of the Gigabyte GV-NX76T256D-RH is going to be as good at overclocking as ours. However, 660MHz is so far the best result we’ve achieved in our labs with a GeForce 7600 GT without extreme overclocking methods (which might have led to even better results).
The memory frequency growth is, on the contrary, moderate. 60MHz isn’t much (for comparison: Samsung K4J52324QC-BC14 chips with the same access time are pre-overclocked to 800 (1600) MHz by the manufacturer on the XFX GeForce 7600 GT XXX Edition graphics card and are absolutely stable at that). It must be the higher voltage of the Infineon chips (2.0V against the Samsung chips’ 1.8V) that resulted in higher heat dissipation, but we aren’t absolutely sure. Perhaps another sample of the Gigabyte GV-NX76T256D-RH would have provided a higher memory frequency growth.