Page 1
| A Guru3D fact |
| One MHz represents one million cycles per second. The speed of microprocessors, called the clock speed, is measured in megahertz. For example, a graphics processor that runs at 600 MHz executes 600 million cycles per second. Each computer instruction requires a fixed number of cycles, so the clock speed determines how many instructions per second that processor can execute. |
Well my friends, let's get this article started, as usual .. in-depth on the architecture.
The Radeon X1900 GT is of course a product of the latest X1000 family of ATI GPUs. The X1900 GT series is priced at a great 300,- USD. This new graphics card is running at a tact frequency of 575 MHz accompanied with it's memory running at (2x600MHz) 1.2 GHz. Speaking about memory, it's gDDR3 memory and there's 256MB of it.I would not be rather shocked to see the GT work with an XT BIOS, why ? Because this is the same chip with a couple of things disabled. It looks like this products come from the same product line. So yeah .. correct .. it's the same chip yet is has less pixel pipelines and shader processors active.
Just like ATI's "concentrated" Radeon X1800 part, the X1800 GTO, the Radeon X1900 GT incorporates the full feature set of the R580 architecture. It however has one internal unit disabled. This means that the number of pixel pipelines in this part is reduced to twelve, which also leaves the core with 36 pixel shader units compared to 48 on a full Radeon X1900. Despite being effectively 'de-activated' from the pixel pipelines in this chip, the number of texture units in the X1900 GT is also reduced to twelve compared to sixteen on a full R580 core.
Cutting down the pipeline in half will have a tremendous effect on performance, something that the 36 pixel shader units will have to make up for. The number of Vertex processors remains the same though, a good eight of them are activated. So, factually seen from a lot of views .. this product is close to the X1800 GTO, yet with some more horsepower under the hood in the form of pixel processors.
The PowerColor X1900 GT is equipped with 256MB 256-bit memory. Samsung K4J55323QG GDDR3 memory rated at 1.4ns to be precise.
1000/1.4= 714 So we see that this memory can be pushed higher than it's default clocks for sure. Something good to know for our overclocking session.
Some miscellaneous features:
- Ultrathreaded Architecture with fast dynamic branching
- 12 Pixel Shader Processors
- 8 Vertex Shader Processors
- 512-bit ring-bus memory controller
- 256-bit memory interface
- DX9 Shader Model 3.0 support
- Simultaneous support for HDR and Anti-aliasing
- Avivo video & display feature set
- H.264 playback acceleration
- Two dual-link DVI outputs
- Full 10-bit display processing & output capability
- CrossFire support
- Single-slot PCI Express board configuration
|
Radeon card |
Pixel Shader Units |
Vertex Shader |
Texture Units |
Core Frequency |
Memory Frequency |
Memory |
Price in USD |
Available |
| X1900 XTX | 48 | 8 | 16 | 650 | 775 | 512 gDDR3 | 549 | Now |
| X1900 Crossfire | 48 | 8 | 16 | 625 | 725 | 512 gDDR3 | 599 | Now |
| X1900 XT | 48 | 8 | 16 | 625 | 725 | 512 gDDR3 | 479 | Now |
| X1900 AIW | 48 | 8 | 16 | 500 | 500 | 256 gDDR3 | 499 | Now |
|
X1800 XT |
16 |
8 |
16 |
625 |
1.5 GHz |
256/512 gDDR3 |
329 /449 |
Now |
| X1900 GT | 12 | 8 | 16 | 575 | 1.2 GHz | 256MB gDDR3 | 299 | Now |
|
X1800 XL |
16 |
8 |
16 |
500 |
1.0 GHz |
256MB gDDR3 |
449 |
Now |
| X1800 GTO | 12 | 8 | 16 | 500 | 1.0 GHz | 256MB gDDR3 | 249 | Now |
|
X1600 XT |
12 |
5 |
4 |
590 |
1.38 GHz |
128 / 256 MB |
199 / 249 |
Now |
|
X1600 PRO |
12 |
5 |
4 |
500 |
780 MHz |
128 / 256 MB |
149 / 199 |
Now |
|
X1300 PRO |
4 |
2 |
4 |
600 |
800 MHz |
256 MB |
109 |
Now |
|
X1300 |
4 |
2 |
4 |
450 |
500 MHz |
128 / 256 MB |
99 / 129 |
Now |
|
X1300 Hypermemory |
4 |
2 |
4 |
450 |
1 GHz |
32 / 128 MB |
79 |
Now |
As you can see in the chart I placed the X1900 GT in a very peculiar position, this is a very oddly placed product performance wise. You'll notice that the more common games will have performance close to the X1800 GTO/XL. Rich Pixel Shaded games will benefit from the 36 pixel shader units and thus all of a sudden the card will position itself much higher in the rankings - close or even higher than a X1800 XT.
You will also notice this in our benchmark session. The product varies a great deal in terms of positioning in performance. The 12 pixel pipelines are hurting it's overall performance, something that the extra pixel shader processors have to make up for bigtime.
