AMD Radeon HD 7950 Review along with XFX and Sapphire Models

Introduction

After the launch of Radeon HD 7970, which is the first card to support DirectX 11.1 and PCI-E 3.0, AMD has now brought another new comer from the GCN series, Radeon HD 7950 with same features of HD 7970. With a good yield, 28-nm manufacturing process has some important benefits. It increases the operating frequency, while decreasing power consumption. With Radeon HD 7970, AMD has introduced a new generation of GPU, characterized by a new production process, a new GCN architecture, a new tessellation unit and a much higher performance than its previous generation graphic cards.

AMD allows the release of overclocked versions from its partners, now itself.  In this review we are going to analyze both XFX and Sapphire Radeon HD 7950 graphic cards, both are clocked higher than the standard version. Today, the Radeon HD 7950 will be in higher volumes with the main distributors.  Radeon HD 7950 is priced at $449 for the current 3 GB version, which is $100 lesser than HD 7970, thereby bringing the extreme gaming to sub $500 level.

AMD Radeon HD 7950 GCN Architecture

AMD had used VLIW (Very Large Instruction Word) architecture for years in the core of its Radeon GPUs, now under the name Radeon HD 7000 series; AMD had replaced VLIW architecture with GCN architecture. Under VLIW, the processing units can work simultaneously on 4 or 5 instructions, each of several elements. With its new GCN architecture, AMD takes a scalar function; this is to work on a single statement block, also on several items at once. A Compute Unit, which consists of SIMD blocks (four per CU), can execute an instruction on up to 16 elements.

Since AMD had implemented a new architecture, it has reviewed its schedulers too, thereby optimizing power calculation units. Specifically, Tahiti can work on a larger number of items at once. Depending on the workload, the architecture will gain more or less significant as it has clearly been designed for maximum efficiency in compute process that is during the process of video encoding, decoding acceleration, etc. instead of 3D. Meanwhile, the architecture of the chip is already compatible with DirectX 11.1, the next version of Microsoft’s API which is to be integrated into Windows 8. Also HD 7950 is made PCI-E 3.0 Compatible.

A Glimpse at Specifications

AMD’s flagship Radeon HD 7970 has 32 CU or Compute Unit, but the Radeon HD 7950 has only 28. These 28 CUs with 4 SIMD, which in turn can work on 16 elements and so we get 1796 stream processors. Though the number of CU is reduced HD 7950 has more than 112 texture units and the number of ROP units remains constant. Also there is no change in terms of memory. Radeon HD 7950 has 384-bit memory bus and 3 GB GDDR5 with 240 GB / s bandwidth according to the official specifications.

Radeon HD 7950 is manufactured by TSMC in 28nm technology and has 4.34 billion transistors. AMD recommends an operating frequency of 800 MHz for core and 1250 MHz for memory. The version released now has 3 GB GDDR5 memory, whereas 1.5 GB versions will be released as per the release date mentioned in our previous posts.

Sapphire Radeon HD 7950

Sapphire Radeon HD 7950 comes with a custom heat sink, characterized by two fans that surmount the radiator. The decision to opt for a cooling system different from the standard solution is to increase the operating frequency much higher than the reference design. The external structure of the board is made up of black plastic: Sapphire prides a switch that lets you to manage a direct control over the two bios present in the card.

In addition to DVI output, there are two mini-DisplayPort and HDMI port. The top of the mounting bracket is intended for the ventilation grill, which is essential for the expulsion of hot air produced by the card. 2 6 pin PCI-E connectors are needed for the proper functioning of the board. Memory modules are cooled by a simple metal plate that covers them. The heatsink is in direct contact with the GPU block with 5 copper heat pipes which channels out the heat produced during operation.

XFX Radeon HD 7950 Black Edition

XFX was an exclusive partner of NVIDIA for some time and now it offers a complete line of Radeon with models that are generally distinguished from reference design. XFX offered two models at launch. The first uses the standard features, set by AMD, but has a cooling system made by XFX while the second takes the same previous system and adds an overclocking, with a Black Edition tag too.

In XFX, the sink is completely enclosed by an aluminum coating, which covers the entire surface of the card. It has 4 outputs, same as the previous card. The DVI connector is colored red; the remaining three connections are 2 mini DisplayPorts and one HDMI port. There are 12 memory modules with 256MB each positioned around the board, operating at an actual frequency of 5500MHz.

XFX has removed the switch that toggles between the two bios. This is a great demerit while considering two important things. One is that HD 7950 is a high end card meant for enthusiasts, so naturally they expect 2 BIOS for convenience. Another thing is that XFX creates a noise similar to GTX 480, which can be normalized by flashing other BIOS if available.

The dissipation block shows a complex structure that not only takes care of cooling the GPU but also the memory modules. This structure provides copper block to take the heat out of the GPU, while in the case of memories, just the thermal paste is used to conduct the heat.

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1. Specifications and a Closer Look
2. Benchmarks
3. Conclusion

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