AMD Radeon HD 7770 & HD 7750 Review
In their march towards a top to bottom 28nm lineup, it was only a matter of time until AMD dropped some products into lower price points. While many expected the next products to hit the market would be the Pitcairn-based HD 7800 series, that wasn’t meant to be (we’ll likely see those in a few weeks) and instead the mainstream HD 7700 cards are being introduced first. Initially this series will be broken into two separate cards: the HD 7770 and HD 7750,which will retail for between $109 and $159. Considering there’s been quite a bit of movement in this price range with the previous generation’s higher performance cards getting some noteworthy price cuts the HD 7700 series could be in for a tough fight.
Under the code name of Cape Verde, the HD 7700 series was developed to be the “graphics cards for everyone” and pick up where the popular HD 5770 and HD 5750 (now rebadged the HD 6770 and HD 6750 respectively) left off. Some may not have realized this but the HD 5770 remains one of the most used DX11 GPUs on the market.
The HD 7700-series leverages a scaled down version of AMD’s Graphics Core Next in order to deliver the best possible DX11 gaming environment. In it’s fully enabled form the Cape Verde core consists of a single Compute Engine with ten GCN compute units consisting of 64 Stream Processors each for a total of 640 SPs. With each compute unit also housing four texture units, a HD 7770 will have a total of 40 TMUs. These are paired up with a single 9th generation tessellator (down from the dual tessellators on higher end cards) and 512KB of L2 read / write cache.
Cape Verde Pro's core has a pair of Compute Engines disabled so it comes equipped with 512 cores and eight less texture units than its bigger brother.
The ROP layout remains identical to higher end cores but have once again they have been cut down. Instead of the eight Render Output Units Tahiti comes equipped with, Cape Verde only uses four, each of which has been outfitted with four ROPs. 16 ROPs may not seem like all that much but AMD has significantly increased their throughput when compared to the previous generation so benefits will certainly be seen in some situations.
In terms of memory support, AMD is going for a top to bottom GDDR5 lineup though this time the four modules will be working off of a 128-bit memory interface with a pair of 64-bit controllers. In theory this should allow for 2GB configurations as well but we highly doubt cards with that type of layout will be available at launch.
The HD 7770 and HD 7750’s feature set mirrors that of higher end products with full Eyefinity multi monitor support and AMD’s App Acceleration coming as standard additions. We’ve covered the benefits of these points in past articles but what should make these two cards stand out from the pack is their support for AMD’s extended UVD 3.0 standards. With truly next generation video decoding capabilities including Blu Ray 3D output and compatibility with the latest codec packages, these two cards could become favorites of the HTPC crowd.
Another item which makes a comeback here is ZeroCore Power which essentially shuts down the core during long idle scenarios, helping to conserve power and increase overall efficiency. PowerTune is also included on these cores to ensure that their power needs don’t exceed a certain preset value.
The HD 7700-series has been parachuted into a lineup that is packed with graphics cards all piggybacking off one another’s price points. With the HD 7770 and HD 7750 being released, AMD now has four products from current and previous generations all within a narrow bracket of just ~$50. The HD 6850 and HD 6790 along with the newest additions are all competing against one another, not to mention certain outsides like the HD 6870 and NVIDIA’s GTX 560 1GB (the non-Ti version) and GTX 550 Ti.
On paper, the HD 7770 is supposed to fill a gap in AMD’s lineup while opening up a new front in the war against NVIDIA. It may not go toe to toe against any present NVIDIA cards from a pricing standpoint (the average price for a GTX 550 Ti is currently $119), many will feel like the HD 5770’s spiritual successor has been born. In addition, the HD 7770 has the distinction of being the first reference based card to reach the 1GHz mark, a fact not lost on AMD’s PR team which has coined the term “GHZ Edition” for cards meeting or surpassing the gigahertz barrier.
The HD 7750 on the other hand is supposed to meet requirements that are a bit more modest in scope. It is meant to go head to head against the GTX 550 Ti while offering a step up from the HD 6770 which has a core that dates back to the Juniper days. At $109 is should offer some much needed value to the budget friendly mainstream consumers.
On one hand the GCN architecture’s built in pipeline refinements should allow it to hold an edge over similarly spec’d cores. In addition, the massive 1GHz operating frequency will surely count for something but the Barts Pro core has brute force and a similar price on its side. For gamers in particular this performance disparity may cause them to avoid AMD’s new cards for the time being.
This situation highlights the challenges posed by introducing products into certain lower end price point where older, lower priced GPUs have yet to run their course. As we mentioned before, the Cape Verde based cards will be competing against more powerful yet less efficient previous generation architectures and will likely face an uphill battle until past SKUs are discontinued.
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