Saturday, October 17, 2009

Radeon HD 5770 and 5750 "Juniper" Jump In


The technology built into the Radeon HD 5870 is propagating to a second GPU in record time. AMD has just introduced a pair of graphics cards based on a new mid-range graphics processor code-named Juniper. Official name is the Radeon HD 5700 series.

Juniper turns out to be quite similar to the RV770 GPU that powers the prior-gen high-end Radeon HD 4800 series. Both Juniper and RV770 have 800 SPs, 10 texture units, four render back-ends, and a single rasterizer. But Juniper is a smaller chip intended for less expensive graphics cards, so it has only two 64-bit memory controllers or an aggregate 128-bit memory interface. Both Cypress and RV770 have 256-bit memory interfaces. Still, the use of higher-clocked GDDR5 memory in the Radeon HD 5700 series will at least help bridge the deficit versus the RV770.

Juniper varies from the RV770 in many other respects. The chip's hardware supports many capabilities exposed in new software APIs like DirectX 11, DirectCompute, and OpenCL 1.0. Don't forget it's manufactured by 40nm fabrication process.


Radeon HD 5770 comes with 10 SIMD engines, cranks away at 850MHz in the 5770, paired with a gig of memory clocked at 1.2GHz. That memory clock translates into a 4.8 GT/s data rate, since this is GDDR5 memory. Happily, Juniper has inherited Cypress's ability to conserve power at idle by dropping its GDDR5 memory into a low-power state. As a result, AMD rates the 5770's idle power at only 18W. Even under load, the 5770 is relatively tame, with a 108W max power rating.

Radeon HD 5750, the 5770's little brother has had one of its SIMD cores clipped, along with the corresponding texture unit. Clock speeds are de-tuned, too, with the GPU at 700MHz and memory at 1150MHz. Thanks to the changes, the 5750 tops out at 86W of power draw and is rated for just 16W at idle.

Another limitation of the 5700 series will be the number of cards supported in CrossFire multi-GPU configurations. Although the cards have dual CrossFire connectors up top, AMD plans to limit them to dual-GPU configs only. Going beyond that will mean moving up to the 5800 series.

The initial suggested e-tail price for the Radeon HD 5770 is $159. The Radeon HD 4870 1GB can be had right now for a prevailing price of about $150 at online retailers. That decision puts the Radeon HD 5770 in more or less direct competition with the GeForce GTX 260, too. Prevailing prices online for the GTX 260 are about $165.

Meanwhile, the 1GB variant of the 5750 will list for $129, where it will have to contend with the Radeon HD 4850 1GB (~$120 prevailing price) and the GeForce GTS 250 1GB (~$140, with some rebates available). Over time, Radeon board makers should begin shipping a 512MB version of the 5750, as well, for around $109.

Game Developers Share Their Thoughts on DirectX 11:


Check out this YouTube video from DiRT 2 showing some of the features that Codemasters incorporated from DirectX 11, creating an incredibly realistic gaming experience:



In this video showcase some of the amazing game-enhancing features that DirectX 11 will bring to the PC version of DiRT 2. The DirectX 11 effects featured in this video are Cloth Tessellation, Hardware Instanced Tessellated Crowd, Tessellated Water with Dynamic Displacement Mapping, Enhanced Lighting and Post Processing. Together these effects make DiRT 2 for Games for Windows Live the most intense, visceral racing game you will have experienced.

More readings here:
Tech Report
AMDZone Review on Sapphire Radeon HD 5770 & 5750
AnandTech
PC Perspective

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