Radeon HD 4830 - another 4-series GPU
In an obvious move, AMD is now introducing a 4-series GPU that will complete the top-to-bottom line-up as far as pricing is concerned.
Borrowing heavily from the Radeon HD 4850, which we covered in detail over here, the 'all-new' Radeon HD 4830 can be thought of as a downgraded, cheaper-to-produce model that doesn't quite make the -50 grade.
Let's roll out the spec table and confirm just what is ticking under the cooler:
| Graphics cards | ATI Radeon HD 4830 512MB (RV770LE) | ATI Radeon HD 4850 512MB (RV770) | ATI Radeon HD 3870 512MB (RV670) | NVIDIA GeForce 9800 GT 512MB (G92) | ||||
|---|---|---|---|---|---|---|---|---|
| PCIe | PCIe 2.0 | |||||||
| GPU clock | 575MHz | 625MHz | 775MHz | 600MHz | ||||
| Shader clock | 575MHz | 625MHz | 775MHz | 1,500MHz | ||||
| Memory clock (effective) | 1,800MHz | 2,000MHz | 2,250MHz | 1,800MHz | ||||
| Memory interface, and size, | 256-bit, 512MB, GDDR3 | 256-bit, 512MB, GDDR4 | 256-bit, 512MB, GDDR3 | |||||
| Memory bandwidth | 57.6GB/s | 64GB/sec | 72.8GB/sec | 57.6GB/sec | ||||
| Manufacturing process | TSMC, 55nm | TSMC, 65nm/55nm | ||||||
| Transistor count | 956m | 956m | 666m | 754m | ||||
| Die size | 260mm² | 260mm² | 192mm² | 296mm²/230mm² | ||||
| Double-precision support | Yes | Yes | Yes | No | ||||
| DirectX Shader Model | DX10.1, 4.1 | DX10, 4.0 | ||||||
| Vertex, fragment, geometry shading (shared) | 640 FP32 scalar ALUs, MADD dual-issue (unified) | 800 FP32 scalar ALUs, MADD dual-issue (unified) | 320 FP32 scalar ALUs, MADD dual-issue (unified) | 112 FP32 scalar ALUs, MADD dual-issue (unified) | ||||
| Peak GFLOPS | 736 | 1,000 | 496 | 504 | ||||
| Data sampling and filtering | 32ppc address and 32ppc bilinear INT8/16ppc FP16 filtering, max 16xAF | 40ppc address and 40ppc bilinear INT8/ 20ppc FP16 filtering, max 16xAF | 16ppc address and 16ppc bilinear INT8/FP16 filtering, max 16xAF | 56ppc address and 56ppc bilinear INT8/FP16 filtering, max 16xAF | ||||
| Peak fillrate Gpixels/s | 6.9 | 10 | 12.4 | 9.6 | ||||
| Peak Gtexel/s (bilinear) | 18.4 | 25 | 12.4 | 33.6 | ||||
| Peak Gtexel/s (FP16, bilinear) | 9.7 | 12.5 | 12.4 | 16.8 | ||||
| ROPs | 12 | 16 | 16 | 16 | ||||
| Peak TDP (claimed) | 110 | 110 | 105 | 105 | ||||
| Power connectors (default clocked) | 6-pin | 6-pin | 6-pin | 6-pin | ||||
| Multi-GPU | CrossFireX - four-board | CrossFireX - four-board | CrossFireX - four-board | SLI - three-board | ||||
| Outputs | 2 x dual-link DVI w/HDCP, HDMI 7.1 (native, on GPU) | 2 x dual-link DVI w/HDCP, HDMI 5.1 (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 | AMD UVD - full H.264 and VC-1 decode | NVIDIA's PureVideo HD 2 - full H.264 decode and partial VC-1 decode | |||||
| Reference cooler | single-slot | single-slot | dual-slot | single-slot | ||||
| Retail price (default-clocked model) | £90 | £115 | £79 | £90 | ||||
Discussion
The table brings together the four current GPUs that ply the £80-£120 market. We've included the previous-generation Radeon HD 3870 512MB because it's still sold in a number of countries.
Talking figures when compared to Radeon HD 4850, the '30 drops two of the HD 4850's 10 SIMD cores - each comprising of 80 stream processors - bringing the total down to 640. Consequently, as two 'cores' have been removed and the texturing subsystem is linked in with each, data sampling and filtering go down a commensurate amount, too. In short, Radeon HD 4830 has 25 per cent less shading and texturing ability, based on a clock-for-clock comparison. The actual drop is higher because the core/shader speed has been reduced, as well.
Fewer stream processors and a chopping of one ROP portion, down from 16 to 12, are matched up to the above-noted lower frequencies, with the core and shaders operating at 575MHz and GDDR3 memory at 1,800MHz. If you're interested, this leads to the Radeon HD 4850 having a 35 per cent higher peak GFLOPs throughput rate, 35 per cent higher fillrate, and 11 per cent higher memory bandwidth.
What we can determine from these numbers is that HD 4830's 3D performance will be around 80 per cent of its bigger brother's, and pricing is such that the RRP is also around 80 per cent - it all makes rather tidy sense.
Number summary
The new Radeon HD 4830 512MB card is a direct derivation of the HD 4850 that was released a few months ago. Our analysis reckons that the LE variant is based on GPUs that don't quite make the full RV770 grade. Why waste them when they can be re-used as lower-priced SKUs, and that's exactly what the HD 4830 is.
