AMD Radeon HD6990 Review

The AMD HD6990 looks pretty much as we expected, with the traditional red fan occupying the center of cooler. As this is a reference board direct from AMD, we don't receive other peripherals in a ‘bundle' package, but we will be looking at partner cards shortly.

The PCB has a protective backplate covering the components, with both GPU mounting blocks visible from the rear.

The card is crossfire capable, and to the right is a bios switch, which we have seen on other AMD cards recently for bios modifications. The AMD HD6990 will ship in the default position of ‘2'. This is a factory supported clock setting (830mhz) with voltage set to 1.12. Position ‘1' is a ‘hardware' overdrive option with increased clocks, 880mhz on the core and an increased voltage setting of 1.175. They are naming this the ‘AUSUM' or ‘Antilles Unlocking Switch for Uber Mode', which we don't expect to become a widely used acronym.

Interestingly, the press pack highlights that the ‘AMD product warranty does not cover damages caused by overclocking, even when overclocking is enabled via AMD software and/or the Dual-BIOS Function'. Not sure how much water that would hold in a small claims court. For now, if you are worried about your investment, best leaving the switch in Position 2.

Retail boards will ship with a cover on this switch with information in the bundle as to what exactly it does, and possibly information on invalidating the warranty.

Connectivity is offered by 4x miniDP connectors (DP 1.2), and a single DL-DVI port.

AMD have informed us that partners will bundle displayport to DVI adapters with their cards, such as those seen above. 3 adapters will ship with every HD6990, a miniDP to SL-DVI passive, a miniDP to SL-DVI active, and a miniDP to HDMI passive.

The card requires two 8 pin power connectors to operate. Obviously if you are powering one of these cards we would recommend a quality power supply.

AMD are using 4GB of quality Hynix H5GQ2H24MFR memory rated to 6ghz.

AMD advised reviewers to avoid disassembling the card until the testing was completed. They are using a ‘phase change TIM' which, apparently, offers 8% better thermal performance. When the connection is broken between GPU core and cooler, the TIM has to be removed. We reapplied quality Noctua NT-H1 thermal paste after the review was completed and we can't say we noticed much difference.

AMD are using the latest generation digital programmable Volterra regulators on the card, to deliver increased efficiency with higher current capacity. The regulators are located at the centre of the board, in a symmetrical layout, to provide efficient power delivery to each GPU and its associated memory. Premium ASICs are screened for high speed and low leakage properties.

Above, GPUz highlights the two different BIOS settings available from the switch on the PCB. AMD class this as ‘HD6990 OC' mode and we will be testing with both settings later.

Same form factor as the HD5970 … bigger than the Cayman cards.

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