AMD Radeon HD 6990 Review: Antilles Has Arrived

Before we dive right in and inspect the Radeon HD 6990, let’s take a minute to look at its main features and specifications. Keep in mind as you look at the chart below that the card is built around a pair of GPUs, so some attributes are split between the two chips.

In its default, non-overclocked configuration, the Radeon HD 6990 has an 830MHz GPU frequency (@1.12v), with 1,250MHz memory (5.0Gbps effective data rate). There is 4GB of on-board frame buffer memory—2GB per GPU. There are a total of 3072 stream processors enabled, 192 texture units, and 64 ROPs. If you add all of this up, what it amounts to is roughly 2x of everything available on a reference Radeon HD 6970, save for the GPU clock (reference Radeon HD 6970 cards are clocked at 880MHz).

All of that horsepower requires a significant amount of juice to operate, so two supplemental 8-pin PCI Express power connectors are necessary with the Radeon HD 6990. And typical load board power can approach 375 watts, which is the maximum rating for a board with this power connector configuration (150 watts per 8-pin feed plus 75 watts from the PEG slot). Interestingly enough, as we mentioned on the previous page, with the flip of a switch, the Radeon HD 6990 can be run in an overclocked mode that pushes the GPU clock to 880MHz (@1.175). With the GPUs running at the higher clock and voltage, board power can exceed 415 watts, which also exceeds the power specifications, so using this mode is going to require a potent PSU. Powertune is configured to not exceed 375 watts when the 6990 is running in its stock configuration, but that number is upped to 450 watts when overclocked.

The Radeon HD 6990 is a full 12” long and the entire card is encased in a fan shroud on the front and a heavy duty metal heat-spreader on the back. A barrel-type cooling fan, common on all recent Radeons resides smack-dab in the middle of the card, which forces air across two heatsinks on either side, which are affixed to the pair of GPUs. Some of the heated air is expelled from the system through vents in the card’s mounting bracket, while the rest is exhausted out of the back of the card and into the system. In addition to making sure a system even has the room to fit a beast like this, good case cooling is also a must.

The output configuration on the Radeon HD 6990 consists of four mini-DisplayPort connectors and single dual-link DVI port. This card obviously supports AMD’s Eyefinity multi-display display technology and can drive up to five displays simultaneously. We should also note that the 6990, when used with an upcoming set of Catalyst drives will support 5x1 portrait Eyefinity configurations, which would make for some truly immersive gaming to say the least.
In a couple of the shots above, the BIOS switch which alternates between overclocked and stock configurations is visible, as are the output connectors, the card’s CrossFire bridge connector (yes, CrossFireX is supported) and board power connectors.

Physically, the Radeon HD 6990 is just a touch shorter than a Radeon HD 5970, due to the slight protrusions on the back of the 5970.