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Review: Sapphire Radeon HD 4850 X2: another AMD-based thorn in NVIDIA's side

by Parm Mann on 4 November 2008, 12:13

Tags: Radeon HD 4850 X2, AMD (NYSE:AMD), Sapphire, ATi Technologies (NYSE:AMD), PC

Quick Link: HEXUS.net/qap2f

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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.