- 40nm process technology
- 826 million transistors
- 137mm2 die size
- 512MB GDDR5 memory
- DirectX 10.1 support
- 640 Stream Porcessing units
- 24x Custom Filter Anti-aliasing
- Dual mode ATI CrossfireX multi-GPU support for highly-scalable performance
- PCI Express 2.0 support
- Dynamic geometry acceleration
- Game physics processing capability
- ATI AVIVO HD video and display technology
- Unified Video Decoder 2 (UVD 2) for Blu-ray and HD Video
- Acceleratd Video Transcoding (AVT)
- DVD Upscaling
- Dynamic Contrast
- Built-in HDMI with 7.1 surround sound support
- Dynamic Power management with ATI PowerPlay technology
- ATI Stream technology
|
Brand Name |
XFX
|
|
Part Number |
HD-477A-YDFC
|
|
Graphics Chip |
RV740
|
|
Core clock |
750
|
|
Shader Clock |
750
|
|
SPs |
640
|
|
Fabrication Process |
40nm
|
|
Transistors |
826 million
|
|
Memory clock |
3200MHz
|
|
Memory bus |
128-bit
|
|
Memory bandwidth |
51.2GB/second
|
|
Memory Size |
512
|
|
ROPs |
16
|
|
Texture Filtering Units |
32
|
|
Texture Filtering Rate |
24 Gigatexels/second
|
|
HDCP Support |
Yes
|
|
HDMI Support |
Yes (via adapter)
|
|
Connectors |
Dual DVI-I, AV-Out
|
|
RAMDACs |
400MHz
|
|
Bus |
PCI Express 2.0
|
|
Form Factor |
Dual Slot
|
|
Power Connectors |
6-pin power
|
ATI introduced the HD 4870 last year with some fanfare as it competed rather well on price/performance/features against NVIDIA's best cards the GTX 260 in the same category. The HD 4770 is based upon their RV740 chip which has 826 million transistors, 640 SPs (instead of 800) split into 128 5D vector cores instead of the 160 on the HD 4870.
Cards based upon the RV740 chips were the first desktop video cards to be based upon TSMC's latest 40 nanometer process. Thus, while the chip has 826 million transistors compared to the 514 million on the HD 4670 that the chip replaced, the die size on the chip is actually smaller at 137mm2 versus the 146mm2 found on the HD 4670. The smaller process also allowed ATI to have less power requirements versus the previous generation.
The HD4770 has a memory bandwidth bus of 128-bit. One advantage of this card is the use of GDDR5 memory, which effectively doubles memory bandwidth when compared to a card using GDDR3 memory like the NVIDIA competition. The memory clock speed of the HD 4770 card is 800MHz which translates into an effective 3200MHz memory clock speed. The card has a memory bandwidth of 51.2GB/second which is similar to the memory bandwidth of the HD 4830 which is analogous to this card on 55 nanometers.
There has been a lot of debate on the merits of DirectX 10.1 versus DirectX 10.0. The fact remains that there are three titles on the market that support DirectX 10.1 features, meaning that it is not as well used as PhysX is in games. On the other hand DirectX 11 requires DirectX 10.1 support so it is better to support DirectX 10.1 than not to. In any event, it will kind of be like the Pixel Shader 1.4 of the Radeon 8500 series. By the time that the majority of games require DirectX 10.1, we will have moved on to the next thing.
ATI introduced Crossfire technology with their x800 video cards in 2005. Crossfire works on ATI motherboards and Intel motherboards with more than one PCI Express x16 slot and up to four ATI video cards. They also released two chip cards, the HD 3870 x2 and HD 4870 x2 that can work in Crossfire mode as four chips. Crossfire improves performance in games by up to 3.2x when three chips are used. To install Crossfire onto a system you need two or more video cards, a motherboard with two or more full length slots and Crossfire bridges.
