Radeon HD 4790 vs Radeon HD 4890 1GB

Intro

The Radeon HD 4790 comes with clock speeds of 600 MHz on the GPU, and 800 MHz on the 512 MB of GDDR5 RAM. It features 640(128x5) SPUs along with 32 Texture Address Units and 16 Rasterization Operator Units.

Compare those specs to the Radeon HD 4890 1GB, which makes use of a 55 nm design. ATi has set the core speed at 1000 MHz. The GDDR5 RAM works at a speed of 975 MHz on this particular card. It features 800(160x5) SPUs as well as 40 Texture Address Units and 16 ROPs.

Price Comparison

Please note that the price comparisons are based on search keywords, and might not be the exact same card listed on this page. We have no control over the accuracy of their search results.

Radeon HD 4790 Amazon.com Other US-based stores Amazon.co.uk Amazon.de Amazon.fr

Radeon HD 4890 1GB Amazon.com Other US-based stores Amazon.co.uk Amazon.de Amazon.fr

Specifications

Model	Radeon HD 4790	Radeon HD 4890 1GB
Manufacturer	ATi	ATi
Year	2009	Apr 2, 2009
Code Name	RV790	RV790 XT
Fab Process	55 nm	55 nm
Bus	PCIe 2.0 x16	PCIe 2.0 x16
Memory	512 MB	1024 MB
Core Speed	600 MHz	1000 MHz
Shader Speed	N/A MHz	(N/A) MHz
Memory Speed	800 MHz	975 MHz
Unified Shaders	640(128x5)	800(160x5)
Texture Mapping Units	32	40
Render Output Units	16	16
Bus Type	GDDR5	GDDR5
Bus Width	256-bit	256-bit
DirectX Version	DirectX 10.1	DirectX 10.1
OpenGL Version	OpenGL 3.0	OpenGL 3.0
Power (Max TDP)	N/A watts	190 watts
Shader Model	4.1	4.1
Bandwidth	102400 MB/sec	124800 MB/sec
Texel Rate	19200 Mtexels/sec	40000 Mtexels/sec
Pixel Rate	9600 Mpixels/sec	16000 Mpixels/sec

Memory Bandwidth: Bandwidth is the max amount of information (counted in MB per second) that can be transported over the external memory interface in one second. The number is worked out by multiplying the interface width by the speed of its memory. If the card has DDR RAM, it should be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The higher the card's memory bandwidth, the faster the card will be in general. It especially helps with AA, High Dynamic Range and high resolutions.

Texel Rate: Texel rate is the maximum number of texture map elements (texels) that are applied in one second. This is calculated by multiplying the total number of texture units of the card by the core clock speed of the chip. The higher the texel rate, the better the card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels per second.

Pixel Rate: Pixel rate is the maximum amount of pixels the video card could possibly record to its local memory in one second - measured in millions of pixels per second. The figure is calculated by multiplying the amount of Raster Operations Pipelines by the the card's clock speed. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel rate is also dependant on many other factors, especially the memory bandwidth of the card - the lower the memory bandwidth is, the lower the ability to reach the max fill rate.