Radeon HD 4890 1GB vs Radeon HD 6850

Intro

Compare that to the Radeon HD 6850, which uses a 40 nm design. AMD has set the core frequency at 775 MHz. The GDDR5 memory is set to run at a speed of 1000 MHz on this particular card. It features 960 SPUs as well as 48 TAUs and 32 Rasterization Operator Units.

Display Graphs

Hide Graphs

Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 6850		127 Watts
Radeon HD 4890 1GB		190 Watts
	Difference: 63 Watts (50%)

Memory Bandwidth

Performance-wise, the Radeon HD 6850 should in theory be a small bit better than the Radeon HD 4890 1GB in general. (explain)

Radeon HD 6850		128000 MB/sec
Radeon HD 4890 1GB		124800 MB/sec
	Difference: 3200 (3%)

Texel Rate

The Radeon HD 4890 1GB is a small bit (more or less 8%) faster with regards to AF than the Radeon HD 6850. (explain)

Radeon HD 4890 1GB		40000 Mtexels/sec
Radeon HD 6850		37200 Mtexels/sec
	Difference: 2800 (8%)

Pixel Rate

The Radeon HD 6850 will be quite a bit (about 55%) better at anti-aliasing than the Radeon HD 4890 1GB, and also will be capable of handling higher screen resolutions better. (explain)

Radeon HD 6850		24800 Mpixels/sec
Radeon HD 4890 1GB		16000 Mpixels/sec
	Difference: 8800 (55%)

Please note that the above 'benchmarks' are all just theoretical - the results were calculated based on the card's specifications, and real-world performance may (and probably will) vary at least a bit.

Price Comparison

Specifications

Memory Bandwidth: Bandwidth is the largest amount of data (in units of MB per second) that can be moved across the external memory interface in a second. It's worked out by multiplying the interface width by the speed of its memory. If it uses DDR memory, the result should be multiplied by 2 again. If it uses DDR5, multiply by 4 instead. The better the memory bandwidth, the better the card will be in general. It especially helps with anti-aliasing, High Dynamic Range and higher screen resolutions.

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

Pixel Rate: Pixel rate is the maximum amount of pixels the video card can possibly write to the local memory per second - measured in millions of pixels per second. The number is worked out by multiplying the number of colour ROPs by the the core clock speed. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel rate also depends on many other factors, most notably the memory bandwidth - the lower the memory bandwidth is, the lower the ability to get to the maximum fill rate.