ATI's "R520" core (codenamed Fudo) is the foundation for a line of DirectX 9c 3D accelerator x1000 video cards. It is ATI's first major architectural overhaul since the "R300" core and is highly optimized for Shader Model 3. The Radeon X1000 series using the core was introduced on October 5, 2005


Variants


X1300 series

The X1300 series is the budget card of the X1000 series. It replaces the X300/X600/X550 series from the previous generation, and shares similar capabilities. The chip carries a 4 pipeline design, similar to those older cards. However, it has all the same capabilities of the higher end boards. In fact, it is said that the chip uses 1 "quad" (4 pipelines per quad), whereas the faster boards use just more of these "quads". For example, the X1800 uses 4 "quads". This modular design allows ATI to build a "top to bottom" line-up using identical technology, saving time and money. Also, the X1300 has more modest power-draw requirements (30 watts), so it runs cooler and fits in smaller cases.

The X1300 series used the RV515 core. There are 3 main variations of the X1300. The HyperMemory variant is quite different from the regular X1300. The local memory is clocked at 400 MHz, higher than the standard X1300, but its bus width is very limited at 32-bit, meaning it has far less available local memory bandwidth. This lowers the cost of the board (to ATI) significantly by reducing board complexity and using fewer and cheaper RAM chips. The onboard memory plays the role of a sort of cache, while most memory operations are performed on system RAM instead. The X1300 Pro gets faster memory, using DDR2 memory as compared to the DDR memory of the normal X1300.

Quite recently, VisionTek, a partner of ATI ported the Radeon X1300 for the PCI-bus. [2] This is ATI's very first DirectX 9 chip available on PCI; until now NVIDIA has had this niche all to itself, except for the now-discontinued XGI Technology Volari V3XT. DirectX 9 on PCI is a rather small niche for now, but with Windows Vista demanding DirectX 9 for its signature Windows Aero interface, it is likely to grow dramatically as those who bought integrated-graphics systems without AGP or PCIe slots in the last few years prepare to upgrade to Vista. The X1300 is also currently the only widely available PCI-Express x1 video card, manufactured by HIS.


X1400 series

A slightly faster Mobility Radeon X1300. Uses the same GPU core as X1300, but with a higher clock speed. Performance comparisons put it well behind X1600 but ahead of X600.


X1600 series

X1600 uses the RV530 core, a core that is quite a bit different from the RV515 of X1300 and the R520 of X1800. The X1600 is positioned to replace Radeon X600 and Radeon X700 as ATI's mid-range GPU.

It shares design philosophy with the X1900, in that it has a far different ratio of pixel shader processors. ATI has stated that the X1600 is designed with a far greater shader computational load, a prediction of future game workloads. Whereas the X1300 and X1800 have an equal pixel shader to texturing unit ratio, which targets a more equal workload of shaders and texturing in games, the RV530 of X1600 alters this to 12 pixel shaders and 4 texturing units. The chip's single "quad" has 3 pixel shader processors per pipeline. This means the chip has the same texturing ability as the X1300 at the same clock speed, but with its 12 pixel shaders it encroaches on X1800's territory in shader computational performance. While the performance is no where near that of an x1800 it still manages to lead the x1300 by a decent margin across the board. The X1600 also receives a boost in the vertex shader department, with the addition of 3 more units (total of 5) over the X1300.

The X1600's core clock speeds are similar to X1300's while the memory attached is usually clocked higher. However, benchmarks shows that the X1600 is a decent step up from the x1300. The reasons for this is that the X1600 while having some of the same limitations has much greater ability to process complex shaders having triple the number of pipelines.




X1700 series

One of possible names for RV570. The RV570 is designed to be an upper mid-range competitor to the 7900GT, carrying the name Radeon X1900GT. RV570 is an 80nm GPU with 12 ROP units, 36 Pixel Shader and eight Vertex Shader Units. Performance is greatly improved thank to inclusion of 256-bit memory interface. The launch date is set for second week of September, availability in late September, beginning of October.




X1800 series

Originally the flagship of the X1000 series, the X1800 series was released with little fanfare due to the rolling release and the gain by its competitor at that time, NVIDIA’s GeForce 7800 series. The reason for the delayed release was that ATI engineers had found a bug within the core caused by a faulty 3rd party 90 nm chip design library which greatly hampered clock speed ramping, and so they had to "respin" it for another revision. The problem had been almost random in how it affected the prototype chips, making it quite difficult to finally identify. When the R520 hit the market in late 2005, the X1800 was the first high-end 90 nm GPU. ATI opted to fit the cards with either with 256MB or 512MB on-board memory (foreseeing a future of ever growing demands on local memory size). The X1800XT PE was exclusively on 512MB on-board memory. The X1800 replaced the R420-based Radeon X850 as ATI's premier performance GPU.

With R520's delayed release, its competition was far more impressive than it would have been if the chip had made its originally scheduled Spring/Summer '05 release. Like its predecessor X850, the R420 chip carries 4 "quads" (4 pipelines each), which means it has similar texturing capability if at the same clock speed as its ancestor, and the NVIDIA 6800 series. Contrasting the X850 however, R520's shader units are vastly improved. Not only are they fully Shader Model 3 capable, but ATI introduced some innovative advancements in shader threading that can greatly improve the efficiency of the shader units. Unlike the X1900, the X1800 has 16 pixel shader processors as well, and equal ratio of texturing to pixel shading capability. The chip also ups the vertex shader number from 6 on X800 to 8. And, with the use of the 90 nm Low-K fabrication process, these high-transistor chips could still be clocked at very high frequencies. This is what gives the X1800 series the ability to be competitive with GPUs with more pipelines but lower clock speeds, such as the NVIDIA 7800 and 7900 series that use 24 pipelines.

X1800 was quickly replaced by X1900 because of its delayed release. X1900 was not behind schedule, and was always planned as the "spring refresh" chip. However, due to the large quantity of unused X1800 chips, ATI decided to kill 1 quad of pixel pipelines and sell them off as the X1800GTO.


X1900 series

The X1900 series fixes several flaws in the X1800 design and adds a pixel shading performance boost. Interestingly, the R580 core is pin compatible with the R520 PCBs meaning that a redesign of the X1800 PCB was not needed. X1900 boards carry either 256 MB or 512 MB onboard GDDR3 memory depending on the variant. The primary change between R580 and R520 is that ATI changed the pixel shader processor per pipeline ratio. The X1900 cards have 3 pixel shaders on each pipeline, giving a total of 48 pixel shader units. ATI has taken this step with the expectation that future videogames will be more pixel shader intensive than previous ones.


X1950 series

The upcoming card based on the R580+ core is said to run at 650 MHz core for both the XTX and Crossfire edition cards. The process technology will likely be TSMC's 90 nm, not 80 nm as was previously reported. The memory used will be Samsung's new GDDR4, which Samsung has tested at up to 3.2 GHz, but the card will most likely ship with the memory clocked at 1.0 GHz (2.0 GHz DDR) for X1950 XT and 1.05 Ghz (2.1 GHz DDR) for X1950 XTX. It is believed that the card's launch will take place in late August 2006.

Benchmarks of the Radeon X1950 XTX in Crossfire have been leaked and showed great improvements; in most of the benchmarks it produced even more frames-per-second than a Quad-SLI enabled GeForce 7950 GX2.