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Redwood and Cedar: Family Portrait

Although we covered the Radeon HD 5670 in an in an earlier review, we want to give you a fuller view of Redwood- and Cedar-based graphics cards. Here is the summary table of their specifications:


Click to enlarge

It is clear that the RV830 core codenamed Redwood is in fact one half of the RV840 (Juniper) core which is used in the inexpensive gaming series ATI Radeon HD 5700. It has half the ALUs, texture-mapping units and RBEs except for the memory subsystem which still has a 128-bit memory bus and allows using different types of memory including GDDR5 and GDDR3/DDR3. The peak memory bandwidth of the more advanced version of the card is 64 GBps which is just slightly lower than that of the Radeon HD 5770. This should not be a bottleneck in the Radeon HD 5670 design. The card’s recommended price is $99, so it falls into the same category as Nvidia’s GeForce GT 24 and everything depends on how effective the drivers and the task dispatcher of shader processors are. In other words, if the Radeon HD 5670 makes use of all its ALUs, it will undoubtedly beat the GeForce GT 240. Otherwise, Nvidia’s solution is going to gain the upper hand, particularly as it has a slightly higher fill rate.

As a multimedia card, the Radeon HD 5670 is theoretically beyond competition because, as opposed to its opponent, it offers full-featured HDMI 1.3a support including bitstreaming of multichannel high-definition audio formats. Nvidia’s products do not support the Protected Audio Path which allows transferring Dolby True HD and DTS HD/DTS HD Master Audio via HDMI. It must also be noted that, like the Cypress and Juniper, the Redwood has two 1080p decoders which are necessary to display stereo 3D content in MPEG4-MVC format (Blu-ray 3D).

One step lower in the hierarchy there is the Radeon HD 5570. Its model number may be somewhat confusing as it only differs from the Radeon HD 5670 with its clock rates and graphics memory type and could be called 5650. It is much inferior to its senior cousin in one parameter only which is the peak memory bandwidth, but this parameter is only important for playing at high resolutions but neither of these cards can be viewed as purely gaming solutions. Considering its price, the 5570 competes with the GeForce GT 240 GDDR3/DDR3 while the GeForce GT 220 has no chance to stand against it. There exists a cut-down version of Radeon HD 5570 marketed under the name of Radeon HD 5550. The latter has 320 ALUs and 16 TMUs, its core frequency is reduced to 550 MHz, and its memory is slow DDR2. We will leave the Radeon HD 5550 out of this review because we haven’t got any sample of it yet. Moreover, this product is hardly interesting for consumers. It is as helpless as its junior cousin in games whereas the latter is just as good at processing high-definition video and audio (with one exception to be mentioned below) but costs less. We guess the Radeon HD 5550 will find its place in ready-made computers.

The most low-end solution in the ATI Radeon HD series, the Radeon HD 5450 is based on a different GPU developed by AMD especially for cheap products. The core is codenamed Cedar (RV810) and is very compact. Developing the most simple and economical GPU, AMD sacrificed nearly all other parameters, excepting the video engine block (partially) and the audio processor. Like Nvidia’s GT218, the RV810 has 16 unified execution processors but, considering the superscalar Radeon HD architecture, each of these processors incorporates 5 ALUs. Theoretically, this GPU can be five times as fast as its opponent if its task dispatcher should provide all the 80 ALUs with work for that. The Cedar will also have no problems decoding even the most sophisticated HD video formats. Otherwise, it is a blatantly low-end solution that is hardly superior to the Radeon HD 4550 in sheer processing power: both have 8 TMUs and 4 RBEs and their fill rates are similar. The memory bus is 64 bits wide with both these cards and the new card may even come with slow DDR2 memory instead of faster DDR3. It is in video decoding and audio processing capabilities that the Radeon HD 5450 is head above its predecessor as well as above the GeForce 210. The only thing is cannot do is to work with Blu-ray 3D since this format requires simultaneous decoding of two video streams, one for each eye, whereas the Cedar has only one HD video decoding unit. Anyway, this GPU may be a true winner in the low-end category: economical, cold, noiseless but strong enough to cope with any modern video and audio format. In other words, it can make a perfect graphics card for a modern HTPC.

We will discuss three pairs of inexpensive Radeon HD 5000 series cards in this review, each pair consisting of AMD’s reference card and an original product from AMD’s partner.

  • ATI Radeon HD 5670 and Gigabyte GV-R567OC-1GI
  • ATI Radeon HD 5570 and Sapphire HD 5750 1GB DDR3 DP
  • ATI Radeon HD 5450 and Sapphire HD 5450 512MB DDR3 DP

We will take a look at their design and see how good they are in practical applications.

 
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