Graphics Cards Guide

PowerColor Radeon X1900 XT 512MB review

PowerColor Radeon X1900 XT 512MB

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Recouping the Top Spot - The Radeon X1900 Series

The Constant Power Struggle

ATI's Radeon X1800 series should have been out as early as when NVIDIA had their GeForce 7800 series out in the market, but it's just unfortunate that they kept facing manufacturing and yield issues that pushed its launch way back till the last quarter of 2005. Even then, availability was scarce at launch and it wasn't till December when the supply chain had enough to populate most major retail stores. Meanwhile during the delays, NVIDIA was the main profiteer since the GeForce 7800 GTX 256MB was widely available, more affordable and could match up to the Radeon X1800 XT on certain fronts. We stress 'certain' because the Radeon X1800 XT's new architecture and vastly faster clock speeds helped it attain some huge wins against NVIDIA's high-end. However, that lead was short lived as GeForce 7800 GTX 512MB debuted in November with amazingly high clocks as opposed to its 'mainstream' 256MB brother and shattered all performance records held by ATI's Radeon X1800 XT darling. Despite the high performance of NVIDIA's two-slot GeForce 7800 GTX 512MB behemoth, its availability was only barely decent at launch and following which until today, it is difficult to obtain and priced at a high premium. Limited stocks and highly sought after, these are the winning combination for a natural market price hike which has taken place if you consider the SRP of US$649 versus the US$700 and upwards going price currently.

ATI not taking lightly to being pushed back to the passenger seat just soon after its prized Radeon X1800 series was made available, they have been quietly working upon a revised edition of their flagship and have made it available much earlier than anticipated with the new Radeon X1900 series today.

Recouping the Top Spot – The Radeon X1900 Series

The new Radeon X1900 series shares the same overall architecture and features that the Radeon X1800 series boasts, but the core now has one significant change – more shader processors. To be precise, it now has 48 pixel shader processors, triple that in the original Radeon X1800 series and double that of the GeForce 7800 GTX. Take note that the 48 pixel shader processors do not equate to 48 pixel shader pipelines. Both ATI and NVIDIA have approached their GPU architectures differently and they no longer equip their cores with equal number of processing units with the pixel pipeline. Basically a pixel pipeline consists of a pixel shader processor, a texture mapping unit (TMU) and a raster operator unit (ROP). ATI has sort of designed their pixel pipelines such that the pixel shader processors are more independent, while NVIDIA has their ROP units independent. With varying processing emphasis within the GPUs, you can easily foretell that graphics cards from both camps are going to perform dissimilarly for certain games and settings, which we'll all find out in due time.

ATI's new take of packing in vastly more pixel shader processors is simply because they are catering the Radeon X1900 series for forward looking application that would make heavy use of pixel shaders. With more pixel shader processors, the Radeon X1900 has the capability to complete far more shader operations in the same cycle as opposed to it predecessors and the competition and that's what they are banking on. True to this fact, we've seen how the Radeon X1600 series behave with their uneven number of processing units, which give them their distinct performance in forward looking processing models such as the 3DMark05 and the very latest games like FarCry, Half Life 2, Doom3, FEAR and more. Likewise where the Radeon X1900's muscle lies in pixel shader processing, it is bound to chalk up some very interesting performance figures in these new games and further upcoming ones as well. Apart from the bump in pixel shader processors, the rest of the specs are quite similar to its Radeon X1800 counterpart. With that said, let us give you a quick matrix of the Radeon X1900 XT compared to its Radeon X1800 XT brother and the competition:-

The Radeon X1900 XT Compared
Model ATI Radeon X1900 XT 512MB ATI Radeon X1800 XT 512MB NVIDIA GeForce
7800 GTX 512MB
7800 GTX 256MB
Core Code R580 R520 G70 G70
Transistor Count 384 million 321 million 302 million 302 million
Manufacturing Process (microns) 0.09 0.09 0.11 0.11
Core Clock 625MHz 625MHz 550MHz 430MHz
Vertex Shaders 8 8 8 8
Rendering (Pixel) Pipelines 16 16 24 24
Pixel Shader Processors 48 16 24 24
Texture Mapping Units (TMU) 16 16 24 24
Raster Operator units (ROP) 16 16 16 16
Memory Clock 1450MHz DDR3 1500MHz DDR3 1700MHz DDR3 1200MHz DDR3
DDR Memory Bus 256-bit 256-bit 256-bit 256-bit
Memory Bandwidth 46.4GB/s 48.0GB/s 54.4GB/s 38.4GB/s
Ring Bus Memory Controller 512-bit (for memory reads only) 512-bit (for memory reads only) NIL NIL
PCI Express Interface x16 x16 x16 x16
Molex Power Connectors Yes Yes Yes Yes
Other Information
  • CrossFire Ready
  • CrossFire Editions Available
  • CrossFire Ready
  • CrossFire Editions Available
  • SLI Ready
  • SLI Ready

The Radeon X1900 series currently has a few known models – the Radeon X1900 XL, XT and XTX variations. While we've listed the specs of the XT variant which we'll be investigating via PowerColor's latest graphics card to bear this GPU, the XTX version is of course the ultimate performer and the XL presumably fitting in a lower sweet-spot. Clocked at 650/1550MHz and going by the minor increments, we doubt the XTX is going to be a whole lot faster than what we'll be sharing with you today. If you are thinking of doubling your rendering power with these, the Radeon X1900 CrossFire Edition is also available, but it is clocked identical to the Radeon X1900 XT and not the XTX model.


With more processing muscle packing into the Radeon X1900 GPU, you can see that the transistor count has increased by nearly 20% and consequently its die size is larger than the Radeon X1800 GPU too. The larger die size and increased processing capability also come with increased power requirements. According to ATI, the maximum power consumption of the Radeon X1900 series is a staggering 175 watts. However, that's just the absolute maximum and ATI assured us that the R580 core has numerous power saving features implemented. Some of these are hardware clocking, load balancing, dynamically altering the number of actual shaders in operation, dynamic clocking of various internal and external clocks among others. Some of these are already present in the X1800 series and even NVIDIA's own GeForce 7800 series. Since the Radeon X1900 series is targeted at the ultimate enthusiasts, ATI themselves aren't actually too concerned with the sky-high power consumption figures since their boards are designed to deliver the highest performance. We'll soon be checking those speed claims, so read on as we showcase PowerColor's Radeon X1900 XT 512MB graphics card and swiftly following it up with the performance figures.