Take Two
Before we get to benchmarks, here's how a pair of 1GB Radeon HD 5870s configured in CrossFireX stack up to the rest of AMD's high-end range. Knowing that one Radeon HD 5870 is the fastest single-GPU card currently on offer, the raw power of two side-by-side is indisputable. Here are the figures:
| Graphics cards | Radeon HD 5870 1,024MB (x2 in CrossFireX) |
Radeon HD 5870 1,024MB |
Radeon HD 5850 |
Radeon HD
4870 X2 2,048MB |
Radeon HD
4850 X2 2,048MB |
Radeon HD
4890 1,024MB |
Radeon HD
4870 512MB |
Radeon HD
4850 512MB |
|---|---|---|---|---|---|---|---|---|
| PCIe | PCIe 2.0 | |||||||
| GPU(s) clock | 850MHz | 850MHz | 725MHz | 750MHz | 625MHz | 850MHz | 750MHz | 625MHz |
| Shader clock | 850MHz | 850MHz | 725MHz | 750MHz | 625MHz | 850MHz | 750MHz | 625MHz |
| Memory clock (effective) | 4,800MHz | 4,800MHz | 4,000MHz | 3,600MHz | 1,986MHz | 3,900MHz | 3,600MHz | 1,986MHz |
| Memory interface and size | 512-bit (2x 256-bit), 2,048MB, GDDR5 | 256-bit, 1,024MB, GDDR5 | 256-bit, 1,024MB, GDDR5 | 512-bit (2x 256-bit), 2,048MB, GDDR5 | 512-bit (2x 256-bit), 2,048MB, GDDR3 | 256-bit, 1,024MB, GDDR5 | 256-bit, 512MB, GDDR5 | 256-bit, 512MB, GDDR3 |
| Memory bandwidth | 307.2GB/s | 153.6GB/s | 128GB/s |
230.4GB/s |
127.1GB/s |
124.8GB/s |
115.2GB/s | 63.5GB/s |
| Manufacturing process | TSMC, 40nm | TSMC, 40nm | TSMC, 40nm | TSMC, 55nm | TSMC, 55nm | TSMC, 55nm | TSMC, 55nm | TSMC, 55nm |
| DirectX/ Shader Model | DX11, 5.0 | DX11, 5.0 | DX11, 5.0 | DX10.1, 4.1 | DX10.1, 4.1 | DX10.1, 4.1 | DX10.1, 4.1 | DX10.1, 4.1 |
| Vertex, fragment, geometry shading (shared) | 3,200 FP32 scalar ALUs, MADD dual-issue (unified) | 1,600 FP32 scalar ALUs, MADD dual-issue (unified) | 1,440 FP32 scalar ALUs, MADD dual-issue (unified) | 1,600 FP32 scalar ALUs, MADD dual-issue (unified) | 1,600 FP32 scalar ALUs, MADD dual-issue (unified) | 800 FP32 scalar ALUs, MADD dual-issue (unified) | 800 FP32 scalar ALUs, MADD dual-issue (unified) | 800 FP32 scalar ALUs, MADD dual-issue (unified) |
| Data sampling and filtering | 160ppc address and 160ppc bilinear INT8/80ppc 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 | 80ppc address and 80ppc bilinear INT8/40ppc 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 | 40ppc address and 40ppc bilinear INT8/20ppc FP16 filtering, max 16xAF | 40ppc address and 40ppc bilinear INT8/ 20ppc FP16 filtering, max 16xAF |
| ROPs | 64 | 32 | 32 | 32 | 32 | 16 | 16 | 16 |
| Peak GFLOPS | 5,440 |
2,720 |
2,160 | 2,400 | 2,000 | 1,360 | 1,200 | 1,000 |
| Peak fillrate Gpixels/s | 54.4 |
27.2 |
23.2 |
24 | 20 | 13.6 | 12 | 10 |
| Peak Gtexel/s (bilinear) | 136 |
68 |
52.2 |
60 | 50 | 34 | 30 | 25 |
| Peak Gtexel/s (FP16, bilinear) | 68 |
34 |
26.1 | 30 | 25 | 17 | 15 | 12.5 |
| Connectors (native) | 2x
dual-link DVI HDMI, DisplayPort, HDTV-out, Eyefinity |
2x
dual-link DVI HDMI, DisplayPort, HDTV-out, Eyefinity |
2x
dual-link DVI HDMI, DisplayPort, HDTV-out |
2x
dual-link DVI HDMI, DisplayPort, HDTV-out |
2x
dual-link DVI HDMI, DisplayPort, HDTV-out |
2x
dual-link DVI HDMI, DisplayPort, HDTV-out |
2x
dual-link DVI HDMI, DisplayPort, HDTV-out |
2x
dual-link DVI HDMI, DisplayPort, HDTV-out |
| Current price | £598 (2x £299) |
£299 |
£220 |
£250 |
£200 |
£125 |
£95 | £80 |
The numbers are almost preposterous. Doubling up on cards, as expected, propels the statistics - a pair of Radeon HD 5870s in CrossFireX will provide 64 ROPs and 160 texture filtering units, creating a mind-boggling bilinear filtering capacity of 136Gtexels/s.
Common sense will you tell that performance will be exceptional, but there are a few provisos to be aware of. First and foremost, users need to be wary of the foibles of multi-GPU usage - scaling is rarely linear, and your mileage could vary depending on software support. Secondly, you'll need a board supporting ATI CrossFireX technology, and last but not least, there's the small matter of the initial outlay. At launch, picking up two Radeon HD 5870s could set you back in the region of £600.
Sounds scary, but here's a duo we prepared earlier:
We're about to get into benchmark territory, but for those wanting to know more about the inner workings of AMD's ATI Radeon HD 5870 GPU - and, indeed, Microsoft's upcoming DirectX 11 API - we encourage you to take a look at our in-depth analysis by clicking here. Already clued up? Move straight on.
