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TekSpek GPU - Graphics
AMD Radeon HD 7950

AMD Radeon HD 7950

Date issued:

The best high-end graphics card ?

CPU and graphics processor company AMD released the world's fastest single-GPU graphics card just before Christmas 2011. Known as the Radeon HD 7970 3GB and approximately 20 per cent quicker than NVIDIA's GeForce GTX 580, the new card is based on a brand-new architecture that's called Graphics Core Next (GCN).

Bringing this new GPU architecture to a lower price point is an obvious move that normally takes place a few weeks after the launch of the top-line card. Some six weeks on from the release of the Radeon HD 7970 comes the second-rung offering known as Radeon HD 7950. This TekSpek explains the technology behind this card and just how it fits into the high-end GPU landscape.

The simplest method to illustrate the differences between AMD's two best single-GPU cards can be shown by a table that lists the pertinent specifications:

GPU Radeon HD 7970
Radeon HD 7950
Radeon HD 6970
Radeon HD 6990 (4,096MB)
Codename Tahiti XT Tahiti Pro Cayman XT Antilles
DX API 11.1 11.1 11 11
Architecture GCN GCN VLIW VLIW
Process 28nm 28nm 40nm 40nm
Transistors 4.3bn 4.3bn 2.64bn 5.28bn
Die Size 352mm² 352mm² 389mm² 2 x 389mm²
Processors 2,048 1,792 1,536 3,072
Compute units 32 28 24 48
Texture Units 128 112 96 192
ROP Units 32 32 32 64
GPU Clock (MHz) 925 800 880 830
Shader Clock (MHz) 925 800 880 830
GFLOPS 3,789 2,867 2,703 5,099
Memory Clock (MHz) 5,500 5,000 5,500 5,000
Memory Bus (bits) 384 384 256 2 x 256
Max bandwidtd (GB/s) 264 240 176 2 x 160
Power Connectors 8+6 6+6 8+6 8+8
TDP (watts) 250 200 250 375
GFLOPS per watt 15.15 14.34 10.81 13.6
CrossFireX Support 4-way 4-way 4-way 2-way
Release MSRP £450 £350 £250 £500

Lower performance, but a whole lot cheaper

Don't worry if the numbers don't mean a lot to you; AMD's made a few cuts to the architecture with a view of lowering the retail price from £450 to £350. The Radeon HD 7950's processors - the engine room of the chip - are cut from 2,048 to 1,792 and the texture units from 128 to 112. AMD further reduces performance by lowering both the core and memory speeds for this newer, cheaper card.

The upshot of a snip in the architecture and lower speeds is performance that's around 15 per cent less than the HD 7970's. This performance puts the Radeon HD 7950 on a par with NVIDIA's GeForce GTX 580 card in gaming terms, though AMD's HD 7950 uses significantly less power thanks to a more-efficient manufacturing process. Indeed, the 200W TDP is considered low (read good) for a genuinely high-end graphics card, meaning retail examples from the likes of Sapphire and XFX should be nice and quiet.

You can tie up to four of these HD 7950s together in AMD's multi-GPU technology called CrossFireX, though adding any more than a second card leads to diminishing returns on performance. Like the Radeon HD 7970, this new card has four digital display outputs that comprise dual-link DVI, HDMI and two miniDisplayPort. This means that you can run up to four monitors - for gaming or productivity - through AMD's Eyefinity technology, though adapters may be needed if using the two miniDP ports: these are usually bundled in by the card manufacturer.

Scan shoppers are often on the lookout for products that excel in a certain area. The Radeon HD 7950's conservative frequencies - 800MHz core and 5,000MHz memory - can be easily increased by running a third-party overclocking application. It is not uncommon for the Radeon HD 7950 to scale to 1,100MHz core and 6,000MHz memory, offering a 25 per cent performance boost over the already-fast card.

Eats up full-HD gaming

Putting this all into context, a Radeon HD 7950 can run practically any game at a full-HD (1,920x1,080) resolution with image quality cranked all the way to the maximum. It's also fast enough to provide adequate performance when indulging in three-screen (5,760x1,080-resolution) gaming, and overclocking it further, to the figures quoted above, helps smooth out gameplay.

AMD has engineered a grounds-up graphics architecture and released it with two cards in the Radeon 7900-series family. Both are cutting-edge in design and able to play any game at high resolutions and image-quality settings. Released today, the Radeon HD 7950 is the cheaper of the two, priced from £350. Offering a little less performance than the Radeon HD 7970 but overclocking just as far, enthusiasts are encouraged to put either card on a shortlist for their next high-performance PC build.

A cheaper HD 7950 on the horizon

AMD will also release a Radeon HD 7950 with a 1.5GB framebuffer, or half that of the launch card. Reducing the framebuffer size should push retail costs down to £325, though overall gaming performance may be compromised if you plan on running at extremely high IQ settings or with three monitors - these are situations that demand 2GB-plus of onboard memory. That said, if you game at the 1,920x1,080 resolution common on many 22-, 23-, and 24-inch monitors, the 1.5GB version may well be a very good fit.

Arch-rival NVIDIA isn't sitting on its hands while AMD makes hay, however, as it plans to release its own 'next-generation' GPUs that are currently known by the codename of Kepler. Whether they will be better than AMD's Radeon HD 7900-series is not presently known.

2012 is shaping up to be an interesting year for high-end graphics cards. AMD rules the roost right now with the Radeon HD 7970 and HD 7950, but NVIDIA may well take the performance crown back in the next few months. Offering pragmatic advice, if you want the very best graphics card(s) for a new system build right now, AMD's 7900-series is it. Scan has a full range of Radeon HD 7970 and Radeon HD 7950 cards right over here. Happy gaming!