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Closer Look at AMD Radeon HD 6950 and HD 6970 2GB Graphics Cards

We’ve got two reference cards for our tests (non-reference Radeon HD 6950 and 6970 do not exist at this point, and may never come out at all). The only external difference between them is the sticker with model name on the cooler casing, and the power connectors. Each PCB is covered with the cooling system on the face side and with a decorative aluminum plate on the reverse side.

We call it “decorative” because it has no contact with any PCB elements while its protective properties are rather questionable. Each card is 276 millimeters long and 39 millimeters tall. The hot air from the cooler is partially exhausted through the grid in the top part of the casing, remaining inside the system case. It mostly goes out through the vents in the mounting grid, though.

There are as many as five video connectors there: two DVIs, two mini-DisplayPorts, and one HDMI.

There will be no special Eyefinity-ready Radeon HD 69xx cards. You will be able to connect up to six monitors to any of these cards using a special video hub.

Each model is equipped with two CrossFireX connectors for building multi-GPU configurations consisting of up to four graphics cards.

Next to them there is a small switch for choosing the BIOS the graphics cards will boot from. Yes, the reference Radeon HD 6950 and HD 6970 are equipped with two BIOS chips. One chip is programmable and another is a backup one to be used when the frequency or voltage settings in the first chip have been set too optimistically.

Now let’s see where the reference Radeon HD 6950 (hereinafter on the left) differs from the reference Radeon HD 6970 (hereinafter on the right). The first thing we can notice is the additional power connectors. Radeon HD 6950 has two 6-pin connectors while HD 6970 has one 6-pin and one 8-pin connector.

That’s okay since the senior model is specified to have a peak power draw of 250 watts and the junior - 200 watts. AMD introduces a new parameter, “typical gaming power”, for the Cayman. It is 190 watts for the Radeon HD 6970 and 140 watts for the Radeon HD 6950. The new cards have the same power draw of 20 watts in idle mode.

They also have nearly identical PCBs, save for a few components.

The power circuits are similar, too.

On closer inspection we can see some differences in the markings of the power circuit components.

The Cayman processors of the Radeon HD 6950 and HD 6970 cards are larger than the Barts and measure 389 sq. millimeters, but they still have no heat-spreaders. The GPU of our Radeon HD 6970 was manufactured 8 weeks later than the GPU of our Radeon HD 6950:

The GPU of the Radeon HD 6950 has 1408 unified shader processors and 88 TMUs. The GPU of the Radeon HD 6970 has 1536 unified shader processors and 96 TMUs. Each GPU has 32 raster operators. The default GPU frequency of the HD 6950 is 800 MHz and of the HD 6970 - 880 MHz.

In the power-saving mode the GPU frequency is lowered to 250 MHz and the GPU voltage is reduced from 1.1 to 0.9 volts on the HD 6950 and from 1.175 to 0.9 volts on the HD 6970. The rest of the GPU characteristics have been covered above in the theoretical part of our review and in the specifications table. We can only add that the diagonal distance between the mounting holes of the GPU heatsink is 75 millimeters on each card.

Each card comes with 2048 megabytes of GDDR5 memory in eight FBGA chips from Hynix Semiconductor. The Radeon HD 6950 carries H5GQ2H24MFR T2C chips which work at 1.5 volts voltage and 5000 MHz rated frequency. The Radeon HD 6970 is equipped with H5GQ2H24MFR R0C chips (1.5 volts, 6000 MHz).

As you could see in the specifications table, the Radeon HD 6950 supports 5000 MHz memory frequency while the Radeon HD 6970 clocks its memory at 5500 MHz. This leaves some elbowroom for memory overclocking. When idle, each card lowers its memory frequency to 600 MHz. The memory bus is 256 bits wide. All the memory chips are placed on the face sides of the PCBs.

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