October 27th, 2008
ATI Radeon HD 4870 Overclocking Guide from TechARP
TechArp.com - The ATI Radeon HD 4870 is based on the long-awaited ATI RV770 GPU, which replaces the RV670 GPU that powered the disappointing ATI Radeon HD 3870 GPU. Both RV770 and the older RV670 are built on the same 55 nm fabrication process but that’s where the similarity ends.
The Radeon HD 3870 has 320 stream processors and 16 texture units, delivering a fillrate of 12.4 gigatexels per second. It was also the first graphics card to feature DDR4 memory. Unfortunately, it was much too late and much too slow to pose much of a challenge to NVIDIA, much less a threat.
As alike they are in architecture and fabrication technology, the Radeon HD 4870 couldn’t be more different from its predecessor. The performance boost it delivered was as revolutionary as its predecessor’s was disappointing. This is literally the graphics card that ATI promised years ago and only just got around to delivering.
The ATI RV770 GPU that powers it has 800 stream processors and 40 texture units. That’s 2.5X as many stream processors and texture units. The end result is a GPU with over 2.4X the fillrate of the RV670. In addition, the Radeon HD 4870 is the first graphics card to make use of GDDR5 memory. Unlike GDDR4, this new graphics memory is quad-pumped, literally delivering twice as much bandwidth at the same clock rate as GDDR4 or GDDR3 memory. The use of GDDR5 memory allowed the Radeon HD 4870 to deliver over 115 GB/s of memory bandwidth.
