OverclockingTo find the maximum overclock of our card we used a combination of GPUTool and our benchmarking suite.
The overclocks listed in this section were achieved with the default fan and voltage settings as defined in the VGA BIOS. Please note that every single sample overclocks differently, that's why our results here can only serve as a guideline for what you can expect from your card.
The overclocks of our card are 825 MHz core (10% overclock) and 1060 MHz Memory (6% overclock). Although for a GF100 Fermi-class card this overclock is very respectable, since we saw around 770 MHz on our GTX 480 reference card, and 797 MHz on the ZOTAC GTX 480 Amp! Edition; it's not as stellar as we expected it to be, considering the kind of high-grade components and marketing behind the GTX 480 Lightning.
Overclocked PerformanceUsing these clock frequencies we ran a quick test of Call of Duty 4 to evaluate the gains from overclocking.
The actual 3D performance gained from overclocking is 10.8%.
Temperatures are reasonably low which helps with the power consumption of the GTX 480. In testing for another review I found out that 10°C temperature difference result in about 12 W of power consumption difference. Also it helps to have a lower temperature for additional overclocking with voltage.
Voltage TuningNew section. Please comment how you like it.
It has been a long known fact that overclocking headroom increases as soon as you increase the operating voltage. Until recently, software voltage control on VGA cards has been the exception and most users were not willing to risk their warranty by performing a soldering voltmod. Nowadays almost all current graphics cards have voltage control in order to achieve low power consumption by lowering voltage when in idle or slightly loaded.
In this section we will increase the GPU operating voltage step by step and record the maximum clock speed possible. Voltage is listed as the value that the voltage regulator reports via software, not actual measured voltage. The card was installed in-case, with fan settings at the default, memory will not be overclocked either. If a card has thermal throttling we will reduce the operating frequency to keep performance at maximum for a given voltage. Please note that the fan profile will have an effect on observed temperatures: if the card gets hotter the fan will ramp up to reduce temperatures or keep them from rising fast.
The following graph shows the overclocking potential we saw on our sample. GPU clock is represented by the blue line, which uses the vertical clock scale on the left. The scale starts at the default clock to give a feel for the overclocking potential over the base clock. Temperature is plotted in red using the °C scale on the right side of the graph.
Once we reached a voltage of 1.150 V, the card ran into the 90° temperature limit set by the BIOS which will cause the card to throttle down. This means that maximum performance at the last tested voltage is available at 810 MHz, even though the GPU could probably run higher clocks if temperature was lower. At this point the fan was already running at 100%.
MSI includes Afterburner with the card which is an excellent VGA overclocking tool. It supports changing three voltages (voltages are measured at the measure points):
VCore: 0.96 V ... 1.07 V (default) ... 1.29 V (+20.6%)
VMem: 1.48 V ... 1.58 V (default) ... 1.68 V (+6.3%)
PLL: 0.96 V ... 1.06 V (default) ... 1.11 V (+4.7 %)
Clock ProfilesModern graphics cards have several clock profiles that are selected to balance power draw and performance requirements.
The following table lists the clock settings for major performance scenarios and the GPU voltage that we measured. We measure on the pins of a coil or capacitor near the GPU voltage regulator.
|Desktop||51 MHz||68 MHz||0.96 V|
|Blu-ray Playback||405 MHz||162 MHz||0.97 V|
|3D Load||750 MHz||1000 MHz||1.06 V|