H.264 and VC-1 decoding performance, power-draw and overclocking
H.264 decoding of HD DVD content
AMD and NVIDIA will tell you that current mid-range DX10 hardware is more than just about painting pretty pixels. Additional bolt-ons help with the computationally-expensive business of decoding high-definition content, so we've pitted AMD's Radeon HD 2600 XT against NVIDIA's GeForce 8500/8600.Testing was conducted on the following Microsoft Vista platform:
| CPU | Intel Core 2 Extreme X6800 @ 2.93GHz |
| Motherboard | NVIDIA nForce 680i SLI | Memory | 4GiB DDR2-800 (2 x 2GiB, 5-5-5-12, 2T, 800MHz) |
| HD DVD drive | Xbox 360 HD DVD drive, USB2.0 |
| Hard drive | 500Gb Seagate 7200.10 SATA2 |
| Monitor | Dell 3007WFP |
| Operating system | Microsoft Windows Vista x86 Business Edition (32-bit) |
| Drivers | sample_vista_8.38.9.1-rc2_48912 'performance' driver for ATI card
ForceWare 158.24 for NVIDIA cards |
Playback software | CyberLink PowerDVD Ultra v2911
WinDVD 8.0.8 Platinum |
| HD DVD content | Babel HD DVD, H.264 AVC, ~25MiB/s, 102s playback of chapter 3 |
Overall, then, a high-end setup that should let the cards' video-decode tech work their magic.
Problems
We ran PowerDVD Ultra v2911, supplied by AMD. Ironically, though, video-decoding acceleration was disabled for AMD's Radeon HD 2000-series cards. That left the CPU to bear the brunt of the decoding.
Turning our hand to WinDVD 8.0.8 Platinum, we managed to get Avivo HD/UVD to work. However, audio/visual synchronisation became an issue during playback and, laughably, the driver would force a BSOD when entering full-screen mode.
We couldn't even get AMD's 'stability' driver to install correctly, hence the use of a 'performance' set.
No problems to report during usage of NVIDIA's PureVideo HD for either player, so we've used WinDVD 8.0.8 Platinum to provide the results you see below. Note, though, it's not strictly a fair comparison - AMD's drivers weren't wholly stable.
| Graphics cards | AMD Radeon HD 2600 XT GDDR4 256MiB | AMD Radeon HD 2400 XT GDDR3 256MiB | NVIDIA GeForce 8600 GTS | NVIDIA GeForce 8600 GT | NVIDIA GeForce 8500 GT | Percentage CPU utilisation with WinDVD8 and UVD/PureVideo HD on (lower is better) | 38.86 | 39.22 | 17.21 | 17.31 | 21.29 | Total system load (average) during playback | 218W | 185W | 191W | 190W | 184W |
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UVD's not all it's cracked up to be, judging by the results obtained using the supplied driver from AMD. We've previously seen a Radeon HD 2600 XT decode and display an H.264 film with under 20 per cent utilisation of a mid-range CPU, so, again, it seems as if a sub-optimal driver is causing problems.
The power results are interesting, with the Radeon HD 2600 XT pulling the highest wattage of any card.
Update - 29/06/07
After furious correspondence with AMD over the UVD issues that we encountered and still noting that 64-bit support is unofficial right now, we've managed to, finally, get UVD to interface in the correct fashion under 32-bit Vista. A number of software hacks were employed to ensure compliance, however.We've also added in results from Harry Potter And The Goblet Of Fire, encoded in the pervasive VC-1 codec. We're only comparing the Radeon HD 2400/2600 to NVIDIA's GeForce 8600 GTS this time around.
Another important note to take away is that re-testing was undertaken with PowerDVD Ultra v2911 and not WinDVD, as above. We've left the original results in as reference markers.
| Graphics cards | AMD Radeon HD 2600 XT GDDR4 256MiB | AMD Radeon HD 2400 XT GDDR3 256MiB | NVIDIA GeForce 8600 GTS | Babel: percentage CPU utilisation with PowerDVD and UVD/PureVideo HD on (lower is better) | 15.25 | 15.45 | 10.65 | Harry Potter: percentage CPU utilisation with PowerDVD and UVD/PureVideo HD on (lower is better) | 13.8 | 13.6 | 19.1 | Total system load (average) during playback | 214W | 182W | 190W |
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That's better. UVD working the way it was advertised. We hope to see a revised driver implementing this new tweaks, and we'd be interested to hear from early adopters who experiment with UVD.
The performance figures are pretty much as expected, especially with VC-1, as AMD has top-to-bottom video-decode acceleration.
More power results!
In the table below, we've also included power-draw - based on results on the ASUS P5W-DH and EVGA NF68 platforms of various cards benchmarked earlier:
| Graphics cards | AMD Radeon HD 2600 XT GDDR4 256MiB | AMD Radeon HD 2400 XT GDDR3 256MiB | ASUS EAX1950 PRO 256MiB | XFX GeForce 8600 GT XXX 256MiB | ASUS EN8600GTS 256MiB | Palit GeForce 8500 GT 256MiB | Inno3D iChiLL 7900GS Arctic Cooling Silencer 6 256MiB |
|---|---|---|---|---|---|---|---|
| Idle power (system) | 89W | 66W | 95W | 88W | 90W | 82W | 97W |
| Load power (system) | 132W | 109W | 141W | 130W | 130W | 111W | 134W |
Despite being based on a 65nm manufacturing process, the transistor-heavy AMD Radeon HD 2900 XT still pulls the same kind of full-load draw as any other card in this line-up.
