The HD 7800 series also brings the much vaunted Graphics Card Next architecture to replace the aging VLIW4/VLIW5 designs of previous generations. Feature wise, the HD 7800 series has the same selling points that we've seen from new AMD cards over the last two months, including improvements in process/power efficiency, flexible multi-monitor configurations. We are told that we will not see actual retail cards until 19th March (2 weeks from this post). The consolation is that there will be an impressive array of custom AIB board designs/bloat when it does hit the shops.
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A shorter version of the 7850
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AMD 7870
The 7870 GPU core is clocked at 1000MHz, 11% higher than the HD 6870, and the GDDR5 memory operates at 1200MHz (4.8GHz DDR), which is 14% higher than the HD 6870. The HD 7870 is paired with a 256-bit wide memory bus providing a theoretical bandwidth of 153.6GB/s or 14% more memory bandwidth than the HD 6870. While the HD 6870 typically came loaded with a 1GB frame buffer, the 7870 has been upgraded to 2GB. We've found that when using multi-monitor setups at extreme resolutions, the larger buffer of AMD's cards provide a significant advantage over Nvidia's, which are limited to 1536MB for the most part. he HD 7870's core configuration also differs from the 6870’s. The new card carries 1280 SPUs, 80 TAUs and 32 ROPs, up 14% from 1120 SPUs and 43% more TAUs from just 56. Like the Radeon HD 7970 flagship, the HD 7870 adopts the 28nm design process and is also PCI Express 3.0-compatible. The new interface spec doubles its predecessor's bandwidth to 32GB/s. Unfortunately, no current processor or chipset supports this technology, so we'll have to test it down the road. To feed the card enough power, AMD has included a pair of 6-pin PCI Express connectors -- the same setup you'll find on the HD 6950 and GTX 570 and other demanding boards.
Naturally, the HD 7870 supports Crossfire, though there is just a single connector meaning it is only possible to pair two cards. The only other connectors are on the I/O panel. Our reference sample has a dual DL-DVI connector, a single HDMI 1.4a port and two mini-DisplayPort 1.2 sockets.
All HD 7870s can support a max resolution of 2560x1600 on up to three monitors. With a multi-stream hub using the mini-DisplayPort 1.2 sockets, the card can power up to six screens.
AMD 7850
The core clock frequency has been lowered from 1GHz to 860MHz which has reduced the compute performance from 2.56 TFLOPS to 1.75 TFLOPS, a 32% reduction. At 860MHz the new Radeon HD 7850 is clocked 4% slower than the HD 6870 and 11% higher than the HD 6850.The GDDR5 memory still works at 1.2GHz, which is effectively 4.8GHz DDR. Because the memory bus is still 256-bit wide the bandwidth remains at an impressive 153.6GB/s, which is 20% greater than the old HD 6850.AMD has also kept the card's capacity at 2GB which is the same amount of memory that can be found on the older Radeon HD 6970 and HD 6950 graphics cards. Where the Radeon HD 7850 really differs from its bigger brother is in the core configuration. The HD 7850 has been downgraded to include 1024 SPUs and 64 TAUs (down from 1280/80), while the ROPs remain at 32.At least on this reference board, the Radeon HD 7850 uses the exact same cooler as the HD 7870. Note however that the Radeon HD 7850 lowers its load consumption to 130 watts, 26% less than the HD 7870. The Radeon HD 7850 is a PCI Express 3.0-compatible graphics card just like the HD 7870. The HD 7850 doesn't require but a single 6-pin PCIe power connector. This means Crossfire setups only need a pair of 6-pin PCIe connectors from the PSU, which is a very mild requirement.Finally the same I/O panel configuration has been used: a dual DL-DVI connector, a single HDMI 1.4a port and two mini-DisplayPort 1.2 sockets. All HD 7850 graphics cards support a max resolution of 2560x1600 on up to three monitors. With a multi-stream hub using the mini-DisplayPort 1.2 sockets, the card can power up to six screens.
