AMD Radeon R9 255 OEM vs ATI Radeon HD 4870 Mac Edition
Graphics Processor
| GPU model | Cape Verde | RV770 |
|---|---|---|
| GPU variant | Cape Verde PRX | RV770 XT Mac (215-0669080) |
| Architecture | GCN 1.0 | TeraScale |
| Foundry | TSMC | TSMC |
| Manufacturing process | 28 nm | 55 nm |
| Number of transistors | 1,500 million | 956 million |
| Die size | 123 mm² | 256 mm² |
Graphics Card
| Release date | Dec 21st, 2013 | Jan 6th, 2009 |
|---|---|---|
| Generation | Volcanic Islands | Radeon R700 |
| Production | End-of-life | End-of-life |
| Interface | PCIe 3.0 x16 | PCIe 2.0 x16 |
| Predecessor | Sea Islands | Radeon R600 |
| Successor | Pirate Islands | Evergreen |
| Reviews | — | 135 in our database |
Clocks
| Base clock | 900 MHz | — |
|---|---|---|
| Boost clock | 930 MHz | — |
| Memory clock | 1150 MHz 4.6 Gbps effective | 850 MHz 3.4 Gbps effective |
| GPU clock | — | 750 MHz |
Memory Configuration
| Memory size | 2 GB | 512 MB |
|---|---|---|
| Memory type | GDDR5 | GDDR5 |
| Memory bus width | 128 bit | 256 bit |
| Bandwidth | 73.60 GB/s | 108.8 GB/s |
Render Configuration
| Shading units | 512 | 800 |
|---|---|---|
| TMUs | 32 | 40 |
| ROPs | 16 | 16 |
| Compute units | 8 | 10 |
| Cache L1 | 16 KB (per CU) | 16 KB (per CU) |
| Cache L2 | 256 KB | 256 KB |
Performance
| Pixel rate | 14.88 GPixel/s | 12.00 GPixel/s |
|---|---|---|
| Texture rate | 29.76 GTexel/s | 30.00 GTexel/s |
| FP32 (float) performance | 952.3 GFLOPS | 1,200 GFLOPS |
| FP64 (double) performance | 59.52 GFLOPS (1:16) | 240.0 GFLOPS (1:5) |
Dimensions & Outputs
| Slot width | Dual-slot | Dual-slot |
|---|---|---|
| TDP | 65 W | 150 W |
| Suggested PSU | 250 W | 450 W |
| Outputs | No outputs | 1x DVI1x mini-DisplayPort |
| Power connectors | 1x 6-pin | 2x 6-pin |
| Board number | C750 | B771 |
| Length | — | 250 mm 9.8 inches |
API Support & Features
| DirectX | 12 (11_1) | 10.1 (10_1) |
|---|---|---|
| OpenGL | 4.6 | 3.3 |
| OpenCL | 1.2 | 1.1 |
| Vulkan | 1.2 | — |
| Shader model | 5.1 | 4.1 |
