AMD Radeon HD 7870 & Radeon HD 7850 Evaluation

AMD’s latest generation GPU series is now taking shape. After being overwhelmed by the performance of the Radeon HD 7900 series and disappointed with the high prices of the HD 7700 series, we are excited to see what AMD has to offer with the new HD 7800 series.

Today, the Pitcairn (codenamed) GPUs that make up the Radeon HD 7800 series are released. As you'd expect, the lineup consists of two GPUs: the Radeon HD 7870 and the Radeon HD 7850, which are rated for a range of $ 200 to $ 400.

Like the siblings in the upper and lower price range, the new HD 7800 series is also based on the 28 nm design process and based on the Graphics Core Next architecture from AMD.


A brief summary of the Radeon 7000 series

Back in January, the & # 39; Tahiti & # 39; GPUs, better known as the Radeon HD 7900 series, were released to become the fastest single GPU on the market. At the top of the food chain are the Radeon HD 7970 and HD 7950 with exceptionally fast GPUs. With a retail price of $ 549 and $ 449, respectively, AMD ensures that gamers pay the highest price for these high frame rates.

Next, we faced the Radeon HD 7700 series, code-named & # 39; Cape Verde & # 39; wore. That mainstream series included the Radeon HD 7770 and HD 7750, which are much cheaper at $ 159 and $ 109, respectively. While they delivered solid performance for lower-priced gaming graphics cards, the value for money was less than excellent.

Existing graphics cards like the GeForce GTX 560 and even AMD's own Radeon HD 6850 therefore offer a better value. On the upside, the performance of these lightweight 28nm GPUs per watt was remarkable. Should AMD overhaul their prices, they could become amazing mainstream offerings.


Radeon HD 7870 in detail

The Radeon HD 7870 is surprisingly compact, being 24 cm long and 1 cm shorter than the old HD 6870. For reference, the Radeon HD 7900 series cards are 27 cm long, which makes them difficult or impossible to install in smaller ones medium-sized ATX computer case.

The GPU core is clocked at 1000 MHz, 11% higher than the HD 6870, and the GDDR5 memory operates at 1200 MHz (4.8 GHz DDR), which is 14% higher than the HD 6870. The HD 7870 is with a 256 bit wide paired memory bus with a theoretical bandwidth of 153.6 GB / s or 14% more memory bandwidth than the HD 6870.

While the HD 6870 was normally equipped with a 1 GB image memory, the 7870 was updated to 2 GB. We found that when using multi-monitor setups with extreme resolutions, the larger buffer of the AMD cards gives a significant advantage over those of Nvidia, which are mostly limited to 1536MB.

The core configuration of the HD 7870 is also different from that of the 6870. The new card contains 1280 SPUs, 80 TAUs and 32 ROPs, an increase of 14% compared to 1120 SPUs and 43% more TAUs from just 56.

Like the flagship of the Radeon HD 7970, the HD 7870 also adopts the 28 nm design process and is PCI Express 3.0 compatible. The new interface specification doubles the bandwidth of the predecessor to 32 GB / s. Unfortunately, no current processor or chipset supports this technology, so we'll have to test it later.

The GPU & # 39; Pitcairn XT & # 39; is cooled by a small aluminum heat sink with 30 fins with a length of 11 cm, a width of 6 cm and a height of 2.5 cm. The heat sink is equipped with a thick copper base and three copper heat pipes that help to quickly extract heat from the base of the cooler.

There is a large heat spreader that covers most of the card and cools the card's GDDR5 chips. The heat is dissipated by a 75 x 20 mm fan that sucks air out of the housing and pushes it backwards.

The fan of the HD 7870 works quietly for the most part, but despite the impressive idle consumption of the card, it still chugs up to 175 watts under load, so the fan spins up during a heavy gaming session.

The heat sink and fan are housed in a special case that hides the front of the graphics card. This is a common practice for AMD's flagship products and one that we like to like.

In order to supply the card with sufficient power, AMD has included a pair of 6-pin PCI Express connectors – the same setup as the HD 6950 and GTX 570 and other sophisticated boards.

Of course, the HD 7870 supports Crossfire, although there is only a single port, so only two cards can be paired. The only other ports are on the I / O control panel. Our reference example has a double DL-DVI connector, a single HDMI 1.4a connector and two mini DisplayPort 1.2 sockets.

All HD 7870 support a maximum resolution of 2560 x 1600 on up to three monitors. With a multi-stream hub with the Mini-DisplayPort 1.2 sockets, the card can supply power to up to six screens.

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