Gigabyte provides their own overclocking utility, called GamerHUD, with their 9800 GT. This nifty little application allows the user to not only raise GPU, Shader, and Memory clocks using sliders, but the GPU Voltage as well, which might be able to get Gigabyte cards an extra advantage that others won't have in the overclocking department. Voltages can be raised in .05v steps, but as the 'Apply' button warns, changing these values "might crash the system or cause damages", so we didn't get too crazy here. Real-time temperature and usage graphs in the upper right give the user some feedback as to how their card is faring, although these can obviously not be checked while a benchmark or game has focus.
Starting at 600/1500/900 for the GPU, Shader, and memory speeds, respectively, we found that we could keep on pushing each clock speed higher and higher without and bump in voltage up until we hit 760 MHz on the GPU. Here, we bumped the voltage to 1.20V, which allowed us an additional 10 MHz increase on the GPU, but that was it. Anything beyond that speed, whether or not we raised the voltage, resulted in 3DMark Vantage crashing, but all crashes were handled gracefully by Vista after a failed OC attempt. Our final speeds: 770 MHz for the core, a 1625 MHz Shader clock, and 1050 for the memory at 1.20V. All told, great increases across the board, raising our 3DMark Vantage score by nearly 12% and frame rates by 16-17%.
In direct contrast to our results with GamerHUD and the Gigabyte GV-N98TZL-512H, overclocking the Palit GeForce 9800 GT Super+ 1GB was a bit more frustrating. Figuring that we had a good baseline to start with, we set out in earnest by immediately halving our former increases using RivaTuner as our tool of choice. We were met with a blue screen of death unfortunately.
Deciding to take it a bit slower, we tried tamer clock speeds and started the ball rolling once again. We found that the memory was the first stumbling block as the Qimonda memory wasn't up to the same challenge as the Samsung variety found on Gigabyte's model. At a 960 MHz clock (1920 MHz effective), we starting seeing some anomalies in 3DMark and had to clock back to 955 MHz to clean this up. Soon after, we hit the GPU's ceiling, barely reaching 700 MHz. Trying to hit 700 MHz or faster typically resulted in BSODs, spontaneous reboots, and other driver-related crashes. Considering the two cards have the same core and similar cooling apparatuses (seemingly even better on Palit's card), we would have expected closer overclock numbers, but that wasn't the case.
FINAL OVERCLOCKING RESULTS
Palit GeForce 9800 GT Super+ 1GB
With our overclocked cards running stable, we decided to give 3DMark Vantage another run-through to see what kind of frame rate increases we might be looking at.
The gains we saw on the Palit GeForce 9800 GT Super+ 1GB were good, gaining two fps in the first GPU test, and just over a frame in the second. More importantly, these increases brought the Palit 9800 GT more in line with the similarly overclocked 8800 GT from EVGA. While we were pleased with these results, we were even more impressed by the new numbers seen with the Gigabyte GV-N98TZL-512H. The speed increases we achieved on the core, shader, and memory clocks gave us about a 16-17% boost in performance, easily surpassing all other cards in our face off.