How to make a Radeon HD 5830
We've covered the underlying architecture during the Radeon HD 5870 review in September 2009. The nomenclature indicates that the all-new Radeon HD 5830's foundations are the same.
Here's a basic specification line-up that compares the Radeon HD 5830 against other premium 5-series GPUs.
The transistor-count intimates that it's very much a high-end GPU, hewn from the same silicon as the HD 5850 and HD 5870. We know that the design is based around SIMD engines that are constituted by 80 stream processors each. This means the HD 5870 has 20, the HD 5850 a total of 18, whilst the new GPU pares them down to 14.
The texture-units are attached to the SIMD cores by a ratio of four TU to a SIMD engine and, as a consequence, HD 5830's complement drops to 56. Texture-fillrate is a multiplication of units and engine speed, so 44.8GTexel/s is reasonable.
What about the bottom - missing ROPs?
The first major departure from 5850/5870 is a halving of the back-end ROPs. This is the part of the GPU that deals with image quality in the form of anisotropic filtering and antialiasing. We can comfortably predict that HD 5830 will suffer in instances of, say, 4x AA/16x AF when compared to the higher echelons of the 5800-series family.
Yet AMD keeps memory-bandwidth the same as HD 5850. Knowing this, we can't quite fathom the company's thinking, as the surfeit of bandwidth will be wasted by the inability of the GPU to process heavy-load AA/AF.
Our thinking is that HD 5830 GPUs represent 'failed' HD 5870 silicon at manufacturing partner TSMC. Appreciating that they won't make the HD 5870 grade, we hazard that AMD instructs TSMC to harvest/bin the chips by reducing the SIMD engines and deactivating half the ROPs. The chip's very name, Cypress LE, lends further credence to the thought.
What's also interesting is the maximum board power for the GPU, rated at higher-than-HD 5850 levels, again intimating the recycling of failed HD 5870 parts rather than a grounds-up design for the sub-£200 market.
Just an ASIC
AMD will not be providing reference boards for partners to place their sticker upon, as has been the case thus far with the 5-series GPUs. Rather, via TSMC, it will provide just the GPU and let partners design the board and cooler to their satisfaction. Pragmatically this means that all AIB-manufactured boards will be different, rated to varying power credentials, and AMD quotes the top-level figure in the slide.
Due to be priced at around £190, including VAT, the Radeon HD 5830 is an odd GPU. Looking reasonably impressive with a core speed of 800MHz and GDDR5 memory at 4,000MHz, its Achilles' heel will come when the ROPs are given a thrashing with copious amounts of AA/AF and high-resolution games-playing.
On first glance the pricing would make sense if it was closer to £150, effectively bridging the gap between Radeon HD 5770 and HD 5850, but at £200, a figure which may well be breached on launch, it's fighting against the Radeon HD 5850 - a GPU that's just better in almost every performance-related metric.
