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ASUS Crosshair IV Extreme: Running SLI With the Lucid Hydra Chip

We tested the SLI performance of the ASUS Crosshair IV Extreme board’s Lucid Hydra chip.


Nvidia’s SLI technology gives hardcore gamers the power they need by pairing up multiple graphics cards. To run SLI, not only must the cards be of the same family, the motherboard must also support the SLI technology. When SLI was launched, only boards with Nvidia’s own nForce chipset SLI. The story changed when Intel refused to grant a license allowing Nvidia to make chipsets for Intel CPUs with integrated memory controllers. Despite this, Intel has worked out a deal with Nvidia where latest Intel chipsets (X58, P55, and P67) all support SLI natively (in addition to their CrossFire support).

AMD users are not as lucky, because AMD’s 2006 buyout of ATI essentially halted any further support for SLI on AMD systems. We are not sure whether AMD is actively preventing Nvidia from developing chipsets for their processors, but there is no doubt that AMD wants to sell their brand of graphic cards and promote CrossFire. So it just makes more sense for them to have Nvidia competing for their business.

The last motherboard for AMD platforms that supports SLI is based on the Nvidia 980a chipset. There are few motherboards on the market with the 980a chipset that support the AM3 socket, and they are already becoming outdated due to the lack of SATA 6Gbps and USB 3.0 support. The ASUS Crosshair IV Extreme is the only one that combines these new features and CrossFireX and SLI support via the third party chipset.

We previously reviewed at the ASUS Crosshair IV Extreme based on the AMD 890FX chipset with native support for CrossFire. ASUS added the Lucid Hydra 200 chip for SLI support. We are revisiting the board and testing its SLI performance.

Overview of the Hydra Chip

The Lucid Hydra chip on the Crosshair IV allows the motherboard to run up to four graphic cards. In addition to adding support for SLI, it also allows users to mix Nvidia and AMD graphics card together. It’s something that we’ve always dreamt of. There are three modes supported:

  • A: AMD CrossFire
  • N: Nvidia SLI
  • X: AMD+Nvidia

Setting up the dual cards requires a bit of extra work, but it’s not too bad. In order to run the multi-GPU setup, users would have to first install the graphic cards drivers, then install the HydraLogix driver. Users who wish to update the graphic cards driver must also uninstall the HydraLogix driver first before uninstalling the graphic card driver.

The ASUS Crosshair IV Extreme board is based on the AMD 890FX chipset, and comes with the Lucid Hydra chip, which will support up to three Nvidia cards in SLI and up to four AMD cards in CrossFireX. The CrossFireX is natively supported by the AMD chipset as well as the Hydra chip. In addition, the Hydra chip adds support for up to three cards in SLI or mixed-mode. Be sure to read the manual to see which slots to install the cards and also what type of configurations are available.

The chipset will automatically detect the modes and when the card is installed in the slot, it will automatically enable the multi-GPU by default. Hydra can be disabled in the included program. A little icon residing on the taskbar will launch the application.

While the board and the HydraLogix chip will support up to four cards, the manual for the Crosshair IV motherboard recommends users only install three cards. Currently, Hydra 200 only support single GPU and not dual-GPU cards like the GTX 295 or the AMD HD 5970. In addition, while the chip will support dual and triple cards, the list of games supported for a three-card configuration is very limited. For a list of games supported, check the official driver release on Lucidlogix’s site. Many popular games currently on the market do support dual card configuration.

The good thing about the Hydra chip when it comes to multi-card configuration is that it will not require any bridge, regardless of the mode used. Since the Hydra chip works on profile, the the onboard chip will work its magic at balancing the loads to the video cards. When a frame reaches the HydraLogix Engine, it will analyze the frame and distribute the rendering tasks to the appropriate GPU. In the event of two different performance cards running together, the chip will distribute the load appropriately so the more powerful cards will do more work. Since this is all done within the HydraLogix chip, there is no need to have an external bridge linking the two cards. However, if users are using the two PCI Express slots controlled by the AMD 890FX chipset (slots 1 and 3), they will still need the CrossFire bridge.

The above image shows the HydraLogix engine’s architecture.

Currently, HydraLogix only supports Windows Vista XP2 or Winodws 7 in both 32-bit and 64-bit. However, mixed mode (X mode) will only be supported under Windows 7. When mixing two cards, the performance of the faster card cannot more than twice as high as the performance of the slower card. In addition, like many multi-GPU setup, when pairing cards with two different performance capabilities, the system’s speed will be limited to the slower of the two. It is highly recommended that users pair two similar-performing cards for the best result.

According to the manual, the special features such as CUDA, Open GL, and HD Hardware acceleration are not affected, though DirectX is. Enabling HydraLogix will still offer support for these special features. One caveat is that PhysX can only work on the secondary GPU. Additionally, enabling HydraLogix will disable the Alt+Tab function according to the manual.

Testing & Methodology

We paired up two GTX 470s in SLI on our ASUS Crosshair IV Extreme with the Lucid Hydra CrossLinx 3 chip. We tested the gaming performance with a single GTX 470 and two GTX 470s in SLI.

AMD Phenom II X6 system:

  • AMD Phenom X6 1100T
  • Thermalright SI-128
  • 4 GB Kingston DDR3 @ 1600 MHz 
  • ASUS Crosshair IV Extreme
  • Seagate 7200.12
  • Gigabyte HD5770  Super Overclocked
  • Cooler Master UCP 900W
  • Graphic card: GTX 470 (ForceWare 260.99)
  • Lucid Hydralogix Driver: 1.7.103


Synthetic Benchmarks & Games
3DMark Vantage
3DMark 11
Alien vs. Predator
Dirt 2
Unigine Heaven 2.1
Stalker COP
 Crysis Warhead
Lost Planet 2
Stone Giant


The latest benchmark tool from Futuremark does not yet fully support SLI, and neither does the latest Hydra driver. Here we see the same scores with a single GTX 470 as with two GTX 470s in SLI.

The GTX 470 SLI setup shows a 60% performance increase over a single GTX 470.

Alien vs Predator shows an impressive 90% performance gain for the SLI setup.

Though Dirt 2 is on the list of games supported, we see virtually no gain with the second card. In fact, the average FPS drops with the SLI setup.

In the Unigine Heaven 2 benchmark, we get 87% gain with extreme Tessellation and 89% gain with normal Tessellation.

Lost Planet is on the official list of games supported but the test does not show any performance gain.

S.T.A.L.K.E.R.: CoP shows about 35% performance gain. With the Sun Shafts enabled, the SLI setup shows about 30% gain.

Stone Giant has an impressive 98% gain without any Tessellation, and a whopping 128% gain with high Tessellation enabled. 

Crysis Warhead is also on the official supported game list, but we did not see any performance gain with the Lucid Hydra enabled. In fact, in Crysis Warhead, the result is slightly lower with SLI enabled, similar to Dirt 2.


When we first reviewed the ASUS Crosshair IV Extreme, we had our reservations about the Hydra CrossLinX 3 due to the fact that we did not have the right cards to fully test its capability. Now, armed with two GTX 470s, we can test the SLI performance on the ASUS Crosshair IV Extreme via the Hydra chip. While we do not see performance increases across the board (even when the game does support multi-GPU setups), for the most part, the supported games do show 30-100% performance gain with the second card.

In our testing, the games do run without much issue, even at very high settings. We did encounter a couple of instances where the game shut down, but re-launching the game worked. Overall, there is no major issue.

Multi-GPU setup is a complex business, and it took both AMD and Nvidia quite some time to really work out the kinks and produce a stable, and high-performance driver. The current Hydra driver seems to be stable enough, and offers a decent amount of performance gain for those who wish to run SLI. If Hydra can continue updating their drivers and add support for newer generations of cards and games, this could be a very valuable option.

The lack of native SLI support is certainly a major blow for AMD. While having the Lucid Hydra chip may not be the best solution, it is nonetheless the best option available for AMD users who want a board with the latest technology such as SATA 6 Gbps and USB 3.0 in addition to SLI. It is also a much better option than the SLI hack that is floating around the web. The ASUS Crosshair IV Extreme is currently the only AMD motherboard on the market with native CrossFireX support and ability to run SLI with the CrossLinX 3 Hydra chip.

We want to emphasize a couple things for those looking to run a multi-GPU setup with the Hydra chip. The most essential part is probably picking the right combination of cards. Also, users should not expect that the latest and greatest cards will be supported at launch, because the Hydra driver often needs to be updated in order to support them. In addition, users should stick with Hydra’s recommended drivers for their graphics cards, and keep their Hydra driver up to date. With this in mind, AMD users may also be able to enjoy the power of SLI with their six-core Phenom II processor.

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