Table time
We already know that the Radeon HD 4850 X2 is based on the Radeon HD 4850 that made its debut back in June, and rather than going over old ground, you can find out all about the Radeon HD 4000-series architecture by reading our previous in-depth analysis.
Today, we'll move on swiftly to the spec table to see how the second X2 product to emerge from Radeon's HD 4000 range compares to the market's other high-end contenders.
| Graphics cards | AMD Radeon HD 4870 X2 2,048MB | AMD Radeon HD 4870 512MiB | AMD Radeon HD 4850 X2 2,048MB | AMD Radeon HD 4850 512MB | NVIDIA GeForce GTX 280 1,024MB | NVIDIA GeForce GTX 260 896MB (new) |
|---|---|---|---|---|---|---|
| PCIe | PCIe 2.0 | |||||
| GPU(s) clock | 750MHz | 750MHz | 625MHz | 625MHz | 602MHz | 576MHz |
| Shader clock | 750MHz | 750MHz | 625MHz | 625MHz | 1,296MHz | 1,242MHz |
| Memory clock (effective) | 3,600MHz | 3,600MHz | 1,986MHz | 1,986MHz | 2,214MHz | 1,998MHz |
| Memory interface and size | 512-bit (2x 256-bit), 2,048MB, GDDR5 | 256-bit, 512MB, GDDR5 | 512-bit (2x 256-bit), 2,048MB, GDDR3 | 256-bit, 512MB, GDDR3 | 512-bit, 1,024MB, GDDR3 | 448-bit, 896MB, GDDR3 |
| Memory bandwidth | 230GB/sec | 115GB/sec | 127GB/sec | 63.5GB/sec | 141.7GB/sec | 111.9GB/sec |
| Manufacturing process | TSMC, 55nm | TSMC, 55nm | TSMC, 55nm | TSMC, 55nm | TSMC, 65nm | TSMC, 65nm |
| Transistor count | 1,930M | 965M | 1,930M | 965M | 1,408M | 1,408M |
| Die size | 520mm² (2 x 260mm²) | 260mm² | 520mm² (2 x 260mm²) | 260mm² | 576mm² | 576mm² |
| Double-precision support | Yes | Yes | Yes | Yes | Yes | Yes |
| DirectX/ Shader Model | DX10.1, 4.1 | DX10.1, 4.1 | DX10.1, 4.1 | DX10.1, 4.1 | DX10, 4.0 | DX10, 4.0 |
| Vertex, fragment, geometry shading (shared) | 1,600 FP32 scalar ALUs, MADD dual-issue (unified) | 800 FP32 scalar ALUs, MADD dual-issue (unified) | 1,600 FP32 scalar ALUs, MADD dual-issue (unified) | 800 FP32 scalar ALUs, MADD dual-issue (unified) | 240 FP32 scalar ALUs, MADD dual-issue + MUL (unified) | 216 FP32 scalar ALUs, MADD dual-issue + MUL (unified) |
| Peak GFLOPS | 2,400 | 1,200 | 2,000 | 1,000 | 933 | 805 |
| Data sampling and filtering | 80ppc address and 80ppc bilinear INT8/40ppc FP16 filtering, max 16xAF | 40ppc address and 40ppc bilinear INT8/20ppc FP16 filtering, max 16xAF | 80ppc address and 80ppc bilinear INT8/40ppc FP16 filtering, max 16xAF | 40ppc address and 40ppc bilinear INT8/ 20ppc FP16 filtering, max 16xAF | 80ppc address and 80ppc bilinear INT8/40ppc FP16 filtering, max 16xAF | 72ppc address and 72ppc bilinear INT8/36ppc FP16 filtering, max 16xAF |
| Peak fillrate Gpixels/s | 24 | 12 | 20 | 10 | 19.264 | 16.128 |
| Peak Gtexel/s (bilinear) | 60 | 30 | 50 | 25 | 48.16 | 41.472 |
| Peak Gtexel/s (FP16, bilinear) | 30 | 15 | 25 | 12.5 | 24.09 | 20.736 |
| ROPs | 32 | 16 | 32 | 16 | 32 | 28 |
| Peak TDP (claimed) | 289 | 160 | - | 110 | 236 | 182 |
| Power connectors (default clocked) | 8-pin + 6-pin | 6-pin + 6-pin | 8-pin + 6-pin | 6-pin | 8-pin + 6-pin | 6-pin + 6-pin |
| Multi-GPU | CrossFire - two-board | CrossFire - four-board | CrossFire - two-board | CrossFire - four-board | SLI - three-board | SLI - three-board |
| Outputs | 2 x dual-link DVI w/HDCP, HDMI 7.1 (native, on GPU) | 4 x dual-link DVI w/HDCP, HDMI 7.1 (native, on GPU) | 2 x dual-link DVI w/HDCP, HDMI 7.1 (native, on GPU) | 2 x dual-link DVI w/HDCP, native HDMI 5.1 (via S/PDIF) | ||
| Hardware-assisted video-decoding engine | AMD UVD 2 - full H.264 and VC-1 decode, plus dual-stream decode | NVIDIA's PureVideo HD - full H.264 decode and partial VC-1 decode, plus dual-stream decode | ||||
| Reference cooler | dual-slot | dual-slot | dual-slot | single-slot | dual-slot | dual-slot |
| Retail price (default-clocked model) | £370 | £185 (£220, 1GB version) | £317 (estimated) | £118 (£158, 1GB version) | £293 | £208 |
As with the Radeon HD 4870 X2, it's worth reminding readers that the Radeon HD 4850 X2 is a single-board solution that features two GPUs connected internally via CrossFire. The card itself plugs into a single x16 PCIe 2.0 connector, and that allows for a second card - another Radeon HD 4850 X2, perhaps - to be added to the mix via another PCIe 2.0 slot and CrossFireX. Four-GPU power might be overkill for many users, granted, but the option is there.
Taking a closer look at Sapphire's board, we note that it features 2GB of GDDR3 memory - showing that it's effectively two 1GB Radeon HD 4850s, and therefore accurately reflected by today's prices.
Elsewhere, each of the Radeon HD 4850 X2's GPUs remain the same as the card it's based upon - providing core, shader and memory frequencies of 625MHz, 625MHz, and 1,986MHz, respectively.
