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ATI's Radeon HD 5450 Architecture

ATI Radeon HD 5450: Eyefinity And HTPCs For Everyone?
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Right out of the gate, it's difficult to deny a bit of disappointment in the base specifications ATI's Radeon HD 5450 brings to the table. Until now, all of the 5000-series cards have represented a significant upgrade over their older counterparts. But at this entry-level price point, the new Radeon HD 5450 offers nothing to get excited about.


Radeon HD 4350
Radeon HD 4550
Radeon HD 5450
Shader Processors:
80
8080
Texture Units:
8
88
Color ROPs:
4
44
Fabrication Process:
55nm
55nm40nm
Core Clock:
600 MHz
600 MHz650 MHz
Memory Clock:
400 MHz
800 MHz800 MHz
Memory Bus:
64-bit
64-bit64-bit
Compute Power (GFLOPs):
92
96
104
Transistors (Millions):
242
242
292
Maximum Power:
22W
25W19.1W


Alright, so saying that there's little to get excited about here might even be a bit of an understatement. The numbers suggest that the Radeon HD 5450 is essentially equivalent to a 40nm die shrink of the Radeon HD 4550, with a 50 MHz faster core speed (and of course the value-adds, like DirectX 11 support, which likely contribute to the higher transistor count).

Now for a quick look at the block diagram:

The Radeon HD 5450 is no monster GPU; it's designed for efficiency. According to the block diagram, it contains two SIMD engines, each with four texture units and eight stream processors, and each stream processor with five ALUs, dubbed stream cores. As a result, this GPU boasts 80 stream cores and eight texture units. Note the single 64-bit memory controller attached to a single render back-end. This render back-end contains four color ROP units, resulting in a total of four ROPs over a 64-bit memory interface.

It is unfortunate that that the SIMD engines have been cut in half compared to the GPUs found on the Radeon HD 5670 and higher models that sport a more robust 16 stream processors per. If the 5450 could have only retained this arrangement, it'd be loaded with a total of 160 stream cores and would have likely offered a more pronounced gaming advantage over the Radeon HD 4550.

As it stands, 80 shader cores gives the card approximately 1/20 the processing power of a Radeon HD 5870. This is a parallel step from the 4550 at best. What's really interesting here is that the new Radeon HD 5000-series is, shader core for shader core, slightly slower than the Radeon HD 4000-series. When asked, an AMD representative told us that this is because the newer architecture has been optimized for DirectX 11, and that the transistors were spent on this, in addition to the other new features. We were plainly told to expect the new Radeon HD 5450 to perform between the 4350 and 4550, despite the new card's clock rate advantage. Indeed, the company's Radeon HD 5450 will be replacing both of these older cards.

In any case, with little to look forward to with regard to game performance, it's easy to see that the Radeon HD 5450's purpose is not necessarily 3D-related. Rather, it's to add the 5000-series' features to the entry-level graphics card market. Let's consider those features and how they might impact you.

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