Radeon HD 4790 vs Radeon HD 4870 512MB

Intro

The Radeon HD 4790 uses a 55 nm design. ATi has set the core speed at 600 MHz. The GDDR5 RAM runs at a speed of 800 MHz on this specific card. It features 640(128x5) SPUs as well as 32 Texture Address Units and 16 Rasterization Operator Units.

Compare that to the Radeon HD 4870 512MB, which uses a 55 nm design. ATi has set the core frequency at 750 MHz. The GDDR5 RAM runs at a speed of 900 MHz on this specific card. It features 800(160x5) SPUs along with 40 TAUs and 16 Rasterization Operator Units.

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 4870 512MB Amazon.com Other US-based stores Amazon.co.uk Amazon.de Amazon.fr

Specifications

Model	Radeon HD 4790	Radeon HD 4870 512MB
Manufacturer	ATi	ATi
Year	2009	Jun 25, 2008
Code Name	RV790	RV770 XT
Fab Process	55 nm	55 nm
Bus	PCIe 2.0 x16	PCIe 2.0 x16
Memory	512 MB	512 MB
Core Speed	600 MHz	750 MHz
Shader Speed	N/A MHz	(N/A) MHz
Memory Speed	800 MHz	900 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	150 watts
Shader Model	4.1	4.1
Bandwidth	102400 MB/sec	115200 MB/sec
Texel Rate	19200 Mtexels/sec	30000 Mtexels/sec
Pixel Rate	9600 Mpixels/sec	12000 Mpixels/sec

Memory Bandwidth: Memory bandwidth is the maximum amount of data (measured in MB per second) that can be transported over the external memory interface in one second. It's calculated by multiplying the card's interface width by the speed of its memory. If it uses DDR memory, the result should be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. The better the memory bandwidth, the better the card will be in general. It especially helps with AA, HDR and high resolutions.

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

Pixel Rate: Pixel rate is the maximum amount of pixels the graphics card could possibly write to its local memory in a second - measured in millions of pixels per second. The figure is worked out by multiplying the number of Render Output Units by the the card's clock speed. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel fill rate is also dependant on many other factors, especially the memory bandwidth of the card - the lower the memory bandwidth is, the lower the potential to reach the max fill rate.