Diamond HD 4890 XOC Preview, Part 1
HD 4890 Specifications
From the table it looks like that HD 4890 is the same as a HD4870 with increased clock frequencies. Saying so would do injustice to ATI engineers who have put hard work into making the HD 4890. If you look closely at the table you will notice that the HD 4890 based on the RV790 chip has 3 million more transistors than HD 4870. One thing that the table does not reveal is that the die size of HD 4890 is 282 sq.mm as compared to HD4870’s 260 sq.mm. So is the HD4890 more than a mere overclock on the HD4870 ? Lets see.
HD 4890 was born with one thing in mind, higher clock rates. To achieve this, AMD has retimed the entire circuit inside the RV770 GPU, added a decap ring around the GPU which improves signal quality by lowering the parasitic noise. Due to increase in frequency, this noise has a considerable effect on the memory and GPU stability. The decap ring works by acting as a barrier that cuts down electromagnetic interference. This allows HD 4890 to work at a default core frequency of 850MHz (a 100MHz increase over HD4870), with a HD4890 OC part coming in with at least 900MHz core frequency.
AMD/ATI launched two HD4890 parts.
- Radeon HD 4890 Standard (reference) version
- Radeon HD 4890 OC editions — At least 900 Mhz Core frequency and 3900+ MHz Memory clocks
