ATI Radeon HD 5830 Specifications

If we just talk about the HD 5830 GPU, and the architecture that supports it, then this section is the second most important part of this review. There has been endless conjecture throughout the industry and among enthusiasts about how ATI was going to tweak the basic ingredients in order to hit the sweet spot that exists in the fairly wide performance gap between the HD 5770 and HD 5850. By way of introduction, I'll just say that when a group of journalists recently saw this chart, they had more questions after they saw it than they did before. Fortunately, ATI was very open with us and gave us some insights into the development process, which you can read about in the launch-day feature we did on the ATI Radeon HD 5830.

Specs are very important for this product, because they tell a vital part of the story. However, I believe the most important part is the testing section, where we finally get to see how the HD 5830 performs. Although you might think that pricing belongs in the top two, it has a life of its own, and it's very difficult to accurately predict where the price will eventually settle. The video card market has always been very dynamic, and with the upcoming (we all hope...) introduction of FERMI-based products from NVIDIA, there are going to be some major wrinkles in the market pricing structure that will have to be ironed out pretty quickly. For now, take a look at where the various versions of the HD5000 series end up relative to one another on this price v. performance chart, and remember this is all based on launch pricing...

The HD 5830 is likely built with chips that had a defect that killed one or more of the stream processor units. As anyone who has followed the AMD product line knows, modern processors are designed with the capability of disabling portions of the die. Sometimes, it's done because there are defects on the chip (usually a small particle of dust that ruins a transistor) and all the internal sections don't pass testing. Sometimes it's done with perfectly good chips because the manufacturer needs to meet production requirements for lower cost market segments. Given the well publicized issues with 40nm manufacturing yields at TSMC, I seriously doubt that ATI is crippling perfectly good chips, just to sell more lower-spec cards. With the release of this minor variant, ATI finally has all the major bases covered for cards based on the Cypress class GPUs.

ATI made the decision to reduce the number of Stream Processors a little more aggressively than they did when they created the HD 5850. They "took away" 320 Shaders this time, instead of only 160. This accomplishes two very important things; it keeps the HD 5830 far enough away from the HD 5850 to prevent cannibalizing sales of that very popular card. It also helps ATI "recover" more defective Cypress GPU chips, which is very helpful when your supplier is having extended manufacturing yield problems with their latest technology node. The downside to only having 1120 Stream Processors is that the GPU had to run a fairly high clock rate in order to hit the performance target that was the whole reason behind this product's very existence. ATI wanted the HD 5830 to hit the exact middle of the performance gap between the 5770 and 5850, too far one way or the other and you haven't really filled the gap. Based on their internal testing, ATI feels they hit the mark. Pay attention to the scaling of this chart....the key takeaway is how close to the middle, between the high and low bars on the left and right, that the HD 5830 bar lands.

So, the stock clock for the HD 5830 came to be set at 800 MHz, and we have the strange situation where the lower performing HD 5830 actually needs more power than the HD 5850, which normally runs at a relatively slow clock rate of 725 MHz when it leaves the factory. This turns out to have the unintended consequence of requiring the HD 5830 boards to have a more robust power supply than the HD 5850. Indeed, the guidance given to the AIB partners was to use the power supply specs from the HD 5870 when designing their boards for the HD 5830. I'm sure the Electrical Engineers understood what had happened, but I'm just as sure that the Product Marketing people were having a cow over this thought.

So now we know a little more about why it's built the way it is. Let's look at how it performs with the latest and most sophisticated graphics API Microsoft has released to date. First, a few words about testing methodology.

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