TPU reports ATI designed the Radeon HD 5970 with massive overclocking headroom. You can expect to easily achieve 30 percent gains for the core, and 50 percent for the memory. The card draws up to 284W at standard clockspeeds, but the cooling solution can handle up to 400W and the company used top-notch components to aid overclocking.
While the engine (core) and memory speeds are set at 720/1000 MHz, the unlocked ATI Overdrive lets users take the clock speeds all the way up to 1000/1500 MHz. That's 30% for the core, and a stellar 50% for the memory.
To back such speeds, AMD seems to have splurged heavily on top-notch components on the PCB. To begin with, the PCB holds two high-grade AMD Cypress GPUs, each with all its 1600 stream processors enabled. The GDDR5 memory, while clocked at 1000 MHz or 4 GT/s, is technically rated by its manufacturer to run at 1250 MHz or 5 GT/s. All systems are powered by high-grade digital PWM voltage regulators, with independent Volterra VRM controllers that allow real-time monitoring, and software voltage control. Barring the five-odd cylindrical solid-state capacitors, Japanese pure ceramic surface-mount capacitors are extensively made use of.