Radeon HD 4870 2GB vs Radeon R9 M265X

Intro

Compare all that to the Radeon R9 M265X, which has a clock speed of 575 MHz and a GDDR5 memory frequency of 1125 MHz. It also makes use of a 128-bit memory bus, and uses a 28 nm design. It is made up of 640 SPUs, 40 Texture Address Units, and 16 Raster Operation Units.

Display Graphs

Hide Graphs

Power Usage and Theoretical Benchmarks

Memory Bandwidth

Theoretically speaking, the Radeon HD 4870 2GB should be 60% faster than the Radeon R9 M265X overall, due to its higher bandwidth. (explain)

Radeon HD 4870 2GB		115200 MB/sec
Radeon R9 M265X		72000 MB/sec
	Difference: 43200 (60%)

Texel Rate

The Radeon HD 4870 2GB is much (more or less 30%) more effective at texture filtering than the Radeon R9 M265X. (explain)

Radeon HD 4870 2GB		30000 Mtexels/sec
Radeon R9 M265X		23000 Mtexels/sec
	Difference: 7000 (30%)

Pixel Rate

The Radeon HD 4870 2GB is quite a bit (more or less 30%) faster with regards to full screen anti-aliasing than the Radeon R9 M265X, and also will be capable of handling higher screen resolutions while still performing well. (explain)

Radeon HD 4870 2GB		12000 Mpixels/sec
Radeon R9 M265X		9200 Mpixels/sec
	Difference: 2800 (30%)

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 information (in units of megabytes per second) that can be transferred over the external memory interface in one second. It's worked out by multiplying the card's bus width by its memory clock speed. In the case of DDR memory, the result should be multiplied by 2 once 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 AA, High Dynamic Range and high resolutions.

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

Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics chip could possibly write to the local memory in one second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the number of colour ROPs by the the card's clock speed. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel output rate also depends on many other factors, most notably the memory bandwidth - the lower the memory bandwidth is, the lower the ability to reach the max fill rate.