AMD Radeon HD 7970 Video Card Review

Videocards/VGA Reviews by stefan @ 2012-07-31

Thanks to the new price reductions, the vanilla RADEON HD 7970 from AMD still remains attractive, can deliver quite good performances even at high resolutions as 2560x1440 and when overclocked it becomes a serious competitor even for the Nvidias' flagship, the GTX 680.

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Product Overview

We should all remember the 22th of December when the latest AMD Radeon HD 7900 series has been launched, starting with the HD 7970 card. The GPU takes part from the Southern Islands family made on 28nm process: Tahiti, Pitcairn and Cape Verde, each aimed at a different performance segment.


The new architecture is called GCN (Graphics Core Next) and is a step forward regarding graphics and computing capabilities.




The Tahiti series is aimed at high end enthusiasts, packed with compute units and a 384-bit memory interface, enough to drive the latest games at high resolutions.


The RADEON HD 7970 GPU has 32 compute units, for a total of 2048 individual stream processors. Each board comes with 3GB of high-speed 5.5Gbps GDDR5, hooked up to the 384-bit memory bus to offer an outstanding 264GB/s bandwidth. This kind of engine and memory bandwidth calls for a lot of data, and this is where the PCI-Express 3.0 interface becomes important.


The PowerTune feature puts the GPU in control and it can push its clock to fill up that thermal headroom when it is available. This technology was introduced at the Radeon HD 6900 series and became a standard on the 28nm lineup.




PowerTune is a integrated on-die system of two microcontrollers by which the GPU can calculate its power consumption at any given time and adjust its clock speeds up or down if it detects power headroom (or lack thereof).


The Southern Islands family is the first to use a Zero Power Long Idle state, which we have also described in the previous HD 7770 and HD 7750 reviews. Long Idle is what your system does when you leave it on and walk away, if we leave our system overnight, or even if you go to the bathroom and Windows turns your display off after a few minutes.




When the driver has got the signal that the display has gone black, voltage to the 3D core is cut and also to the memory controller; AMD puts the GDDR5 into a self-refresh mode, they cut voltage to all the display engine and gets us down to a GPU power of less than one Watt or about 2-3W at the board.




The only thing that is kept alive is the PCI-Express interface, used to jump-in and out of this state in milliseconds. This system is also perfect from CrossFire configurations; with Zero power, in a 4-way multi-GPU system, each of the slave cards will drop into a BACO state and go to sleep until they are needed; this means that we can have our 4-card system idling at about 20W of GPU power, less than a single Cayman.


At default, the Radeon HD 7970 will run at 925MHz for the core and 5.5Gbps on the memory. Recently, the higher clocked GHz versions made their way to the market, named GHz editions, meant to blow away the competition.


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Comment from jmke @ 2013/01/08
I've just upgraded my Asus Radeon 6870 to the smaller brother of the card you reviewed, the Asus Radeon HD 7950; to be exact the: ASUS HD7950-DC2T-3GD5-V2

which comes with 900Mhz GPU (instead of stock 800Mhz) and features a 3 slot design for extremely silent cooling; does make a difference

but I meanly picked this card because of this

Full size DisplayPort Output, HDMI out and two DVI; that way I can keep my 3 monitor config without having to look into more adapters

reason for upgrade is because the HD6870 is getting a bit on the slow end at 5760*1200 resolution is recent games; Far Cry 3 was playable at low-med detail setting at ~30fps... with the 7950 that is bumped up to 40fps with high details