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Sapphire Toxic HD 7970 GHz Edition Review: Gaming On 6 GB Of GDDR5

Clock Rates And Power Consumption: Full Load

We're measuring power consumption at three different settings: Sapphire's 1100 MHz factory core clock, the 1200 MHz Lethal Boost mode, and a fixed 1201 MHz frequency that disables PowerTune.

Using Sapphire's factory setting, the Toxic HD 7970 GHz Edition 6 GB quickly drops to 1050 MHz and stays there, affected by the duress of a very demanding workload. Under the effects of Lethal Boost, the GPU clock rate alternates between 1100 and 1200 MHz. At 1201 MHz, it doesn't budge, of course.

Power consumption at Sapphire's factory clock rate is about 296 W, though it spikes up and down as well. Lethal Boost takes the card to about 314 W. The fixed 1201 MHz GPU frequency adds another two watts to the Lethal Boost setting. In other words, the variable clock rate and TDP limits introduced with the Radeon HD 7970 GHz Edition are basically pointless.