Graphics Cards Guide
Meet The Radeon HD 7970 Cards
The Radeon HD 7970 Cards
ASUS Radeon HD 7970 DirectCU II TOP 3GB GDDR5
Overclocked to a GPU Core speed of 1000MHz (75MHz higher than reference), with 5600MHz memory (100MHz higher than reference), ASUS’ champion in this duel also features an improved version of their DirectCU (Direct Copper) thermal cooling system to adapt to this high-end GPU. DirectCU utilizes a dual-fan design with six copper heatpipes in direct contact with the GPU, just as the name implies. Although ASUS claims that DirectCU II improvements include a 20% larger dissipation area and an overall quieter operation than previous versions, take note that the DirectCU II series of coolers have been around for close to a year now. So don't get consumed by the marketing figures but we'll figure out if the cooler is any good later in our results section.
While all Radeon HD 7970 cards feature six-monitor Eyefinity support, most will require a DisplayPort 1.2 MST (Multi-Stream Transport) capable hub to be connected to provide enough monitor connections. This ASUS card however, features six ports on the back plate itself, consisting of two DVI ports and four full sized DisplayPorts. The HDMI port found on the reference HD 7970 has been removed to make way for these ports.
On most Radeon HD 7970 cards, you'll find a dual-BIOS toggle switch on the top of the card. On this ASUS model, this switch has been reconfigured into a DVI switch that changes between dual and single link DVI. To run in six-monitor mode, the DVI switch must be set to single link mode. Dual-link DVI is required to drive very high resolution screens like the 30-inch monitors which usually have a native resolution of 2560 x 1600 pixels. If you'll require this, then you're limited to five screens maximum. So the six-monitor support isn't exactly fuss free and some caveats apply to the monitor configurations used.
ASUS has also brought its DIGI+ VRM digital power delivery design, first seen on its motherboards, to the Radeon HD 7970 DirectCU II TOP. DIGI+ VRM is applied via a 12-phase power design that uses digital voltage regulators to increase power efficiency, widen the voltage modulation range, and improve overall stability and longevity. Power delivery components utilize ASUS’s Super Alloy Power formulation, which reinforces capacitors, chokes, and MOSFETs with better manufacturing and materials to increase heat tolerance and stress resistance.
As with all ASUS cards, their GPU Tweak utility is included for easy overclocking as well as all your monitoring needs.
Sapphire Radeon HD 7970 OC 3GB GDDR5
Sapphire’s offering in this Radeon HD 7970 duel is a factory-overclocked GPU core speed of 950MHz (25MHz higher than reference), with 5700MHz memory (200MHz higher than reference). It uses Sapphire’s Dual-X cooling system, which features five heatpipes strategically located inside a 230mm-long heatsink packed full of aluminium fins.
Unlike ASUS, Sapphire keeps the functionality of the dual-BIOS switch on their Radeon HD 7970. The first setting, which is the shipping default, sets GPU core speed to 950MHz and memory to 5700MHz DDR, while the second setting pushes it to 1000MHz and 5800MHz DDR respectively, putting it on par with the ASUS’ model (in fact, memory clock speed is 200MHz higher in DDR rates). Going hand-in-hand with the increase, the second BIOS also loads a more aggressive fan speed profile and enables a higher GPU voltage to be set.
Connections wise, Sapphire doesn't deviate from AMD's reference template, offering two Mini DisplayPorts, one HDMI port and one DVI port.
For the tinkerers, Sapphire includes their own TriXX overclocking utility with the card.