Lucid makes quite a showing

Last year we met a darling new company by the name of LucidLogix, or just Lucid, that promised to deliver “near linear scaling” on multi-GPU performance without the requirements of SLI or CrossFire. We have finally seen the technology in action on a production level motherboard coming from MSI and even see an AMD and NVIDIA graphics card share the workload!

Even more impressive though, is the demonstrated ability that the HYDRA technology has to combine the performance of an AMD and NVIDIA card in the same system.  This is truly the killer feature that will make you want, no NEED, a HYDRA-based motherboard very soon.

But first, a quick refresher from our preview of the HYDRA technology last year:

What is the HYDRA Engine?

At its most basic level the HYDRA Engine is an attempt to build a completely GPU-independent graphics scaling technology – imagine having NVIDIA graphics cards from the GeForce 6600 to the GTX 280 working together with little to no software overhead with nearly linear performance scaling.  HYDRA uses both software and hardware designed by Lucid to improve gaming performance seamlessly to the application and graphics cards themselves and uses dedicated hardware logic to balance graphics information between the CPU and GPUs.

Why does Lucid feel the traditional methods that NVIDIA and AMD/ATI have been implementing are not up to the challenge?  The two primary multi-GPU rendering modes that both companies use are split frame rendering and alternate frame rendering.  Lucid challenges that both have significant pitfalls that their HYDRA Engine technology can correct.  For split frame rendering the down side is the need for all GPUs to replicate ALL the texture and geometry data and thus memory bandwidth and geometry shader limitations of a single GPU remain.  For alternate frame rendering the drawback is latency introduced by alternating frames between X GPUs and latency required for inter-frame dependency resolution.

How it Works

HYDRA is a dedicated silicon with sole purpose of scaling GPUs.  Though there is no graphics processing logic on the HYDRA chip, what the chip can do is redistribute graphics workloads across multiple GPUs in real-time.  The HYDRA technology also includes a unique software driver that rests between the DirectX architecture and the GPU vendor driver. 

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The distribution engine as it is called is responsible for reading the information passed from the game or application to DirectX before it gets to the NVIDIA or AMD drivers.  There the engine breaks up the various blocks of information into “tasks” – a task is a specific job that HYDRA defines that can be passed to any of the 2-4 GPUs in the system.  A task might be something like a specific lighting effect, a post processing run, a specific model being drawn, etc.  The company founders on hand at the meeting were a little vague about the algorithms that decide how, and what parts, of the DirectX data are going to be defined as “tasks” – it is obvious that this is part of the magic that gives HYDRA its power; it is with these task definitions that the hardware logic can efficiently distribute the work load across many GPUs.

Once the tasks have been created, they are then sent over the PCI Express bus to the HYDRA chip where they are VERY quickly processed and split between 2 to 4 GPUs.  The HYDRA Engine passes off these tasks to the GPU, awaits a result and return of finished data or pixels, and is then responsible for passing that information on to one of the GPUs for final output to a monitor.  At the outset, this doesn’t sound that much different than what NVIDIA and AMD already do with AFR and SFR rendering modes, but after seeing the HYDRA technology at work it is obviously something very different.

By essentially intercepting the DirectX calls from the game to the graphics cards, the HYDRA Engine is able to intelligently break up the rendering workload rather than just “brute-forcing” alternate frames or split frames as both GPU vendors are doing today in SLI and CrossFire.  And according to Lucid all of this is done with virtually no CPU overhead and no latency compared to standard single GPU rendering. 

To accompany this ability to intelligently divide up the graphics workload, Lucid is offering up scaling between GPUs of any KIND within a brand (only ATI with ATI, NVIDIA with NVIDIA) and the ability to load balance GPUs based on performance and other criteria.  The load balancing is based on a couple of key data points: pre-existing knowledge from the Lucid team about the GPU in question and the “response time” of the GPU when being sent data from the HYDRA Engine chip.  The HYDRA driver will actually recognize the GPUs in a system and will estimate how much processing power each holds but will then fine tune that estimate based on real-time performance of the GPU in action.  If a GPU is sent a “task” to perform and the return time on it is slower than expected, the HYDRA engine will back off slightly and send more “tasks” to the less-loaded GPUs.  All of this is updated on the fly, in real time as the game is running.

With the ability to divide up the graphics processing into tasks and monitor GPU load, the HYDRA engine offers up some very interesting types of GPU scaling.  Yes, it can and will sometimes run standard split frame rendering – this is very efficient for per-pixel processing heavy workloads.  However, the HYDRA can also implement some much more interesting divisions of work.

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Click to Enlarge

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Click to Enlarge

What you are seeing above is two monitors, each displaying the workload of a single GPU in a dual 9800 GT configuration.  This of course wouldn’t normally be how a game is presented to users – it is simply a way to demonstrate their technology to the press.  Before the images are merged again you’ll see two very different screens – one has some rendered areas of a level of UT3 with some areas completely in black while the other monitor has the inverse – opposite rendered areas and black areas. 

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Click to Enlarge – merged image on the left, half of the rendered image on the right; notice no floor on the right, etc.

This is the power of the task-driven graphics workload division.  You can clearly see that some of the “items” in the world are being rendered by one GPU while the background and trees by another.  There is no rigid requirement of certain size or shapes of divisions and thus many of problems found in “box rendering” are avoided.  If Lucid is to be believed, this is the division of tasks that are about “even” in required rendering power.  Lucid pointed out there are many other split rendering methods that it uses in the background for games but that demonstrating them to the end users in any way is pretty difficult to do – techniques like blending pixels in a frame buffer for example. 

Even more importantly though is that this rendering method is NOT predefined by any driver profile as with NVIDIA’s and AMD’s SLI and CrossFire technology.  Instead, because of HYDRA Engine’s pre-processing work, the rendering method can and will change throughout the game and sometimes even inside of individual frames.  The HYDRA chip itself does some of this algorithmic work with help from the driver and task setup process. 

What is new for 2009?

So, at a glance, what is new and being announced this year at IDF?  In short – the actual product you can buy.  Lucid and MSI are teaming to announce the “Big Bang” motherboard that sports the HYDRA 200 chip and three fully functional PCIe slots for multi-GPU gaming.  We are told this board will be available sometime in the next 30 days though pricing is still in the air. 

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MSI’s upcoming “Big Bang” motherboard

We have a great video of about 20 minutes in length that looks over this new motherboard, shows a couple of Lucid’s demos on working systems and talks with the co-founder Offir Remez about Lucid’s technology and plans for the future.

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On the “Big Bang” motherboard the Lucid HYDRA 200 and P55 chipset sit side by side.

Obviously there is one thing missing from this video and article: performance results. Lucid did let us see the HYDRA system in action on the combined AMD/NVIDIA system but the company is not releasing performance numbers at this time.  Based on what I saw last year as compared to this year, I am confident that it will achieve competitive gaming performance.  (Sorry we can’t say more, they are really tying our hands here.)  We will have to reserve our final judgment when we test HYDRA 200 in our labs, but if the idea of “universal GPU scaling” interests you, you’ll want to keep checking back for more information on this motherboard very soon.

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This is the most important system running both an AMD Radeon HD 4890 and GeForce GTX 260 and scaling!

There are still some lingering questions I have for the HYDRA technology: are there stuttering issues?  Will day one scaling for new gaming titles be high enough?  We will be getting our answers very soon.  For now though, this is yet another reason to be excited about PC gaming!