LucidLogix Virtu MVP Technology and HyperFormance

While not specifically a feature of the chipset, Z77 will be one of the first chipsets to use this remarkable new technology. LucidLogix was the brains behind the Hydra chip—a hardware/software combination solution to allow GPUs from different manufacturers to work together (as we reviewed the last iteration on the ECS P62H2-A). Lucid was also behind the original Virtu software, designed to allow a discrete GPU to remain idle until needed, and let the integrated GPU deal with the video output (as we reviewed with the ASUS P8Z68-V Pro). This time, we get to see Virtu MVP, a new technology designed to increase gaming performance.

To explain how Virtu MVP works, I am going to liberally utilize and condense what is said in the Lucid whitepaper about Lucid MVP, however everyone is free to read what is a rather interesting ten pages.

The basic concept behind Virtu MVP is the relationship between how many frames per second the discrete GPU can calculate, against what is shown on the screen to the user, in an effort to increase the 'immersive experience'.

Each screen/monitor the user has comes with a refresh rate, typically 60 Hz, 75 Hz or 120 Hz with 3D monitors (Hz = Hertz, or times ‘per second’). This means that at 60 times per second, the system will pull out what is in the frame buffer (the bit of the output that holds what the GPU has computed) and display what is on the screen.

With standard V-Sync, the system will only pull out what is in the buffer at certain intervals—namely at factors of the base frequency (e.g. 60, 30, 20, 15, 12, 10, 6, 5, 3, 2, or 1 for 60Hz) depending on the monitor being used. The issue is with what happens when the GPU is much faster (or slower) than the refresh rate.

The key tenet of Lucid’s new technology is the term responsiveness. Responsiveness is a wide-ranging term which could mean many things. Lucid distils it into two key areas:

a) How many frames per second can the human eye see?
b) How many frames per second can the human hand respond to?

To clarify, these are NOT the same questions as:

i) How many frames per second do I need to make the motion look fluid?
ii) How many frames per second makes a movie stop flickering?
iii) What is the fastest frame (shortest time) a human eye would notice

If the display refreshes at 60 Hz, and the game runs at 50 fps, would this need to be synchronized? Would a divisor of 60 Hz be better? Alternatively, perhaps if you were at 100 fps, woud 60 fps be better? The other part of responsiveness is how a person deals with hand-to-eye coordination, and if the human mind can correctly interpolate between a screen's refresh rate and the output of the GPU. While a ~25 Hz rate may be applicable for a human eye, the human hand can be as sensitive as 1000 Hz, and so having the correlation between hand movement and the eye is all-important for 'immersive' gaming.

Take the following scenarios:

Scenario 1: GPU is faster than Refresh Rate, VSync Off

Refresh rate: 60 Hz
GPU: 87 fps
Mouse/Keyboard responsiveness is 1-2 frames, or ~11.5 to 23 milliseconds
Effective responsiveness makes the game feel like it is between 42 and 85 FPS

In this case, the GPU is 45% faster than the screen. This means that as the GPU fills the frame buffer, it will continuously be between frames when the display dumps the buffer contents on screen, such that the computation of the old frame and the new frame is still in the buffer:

This is a phenomenon known as Tearing (which many of you are likely familiar with). Depending on the scenario you are in, tearing may be something you ignore, notice occasionally, or find rather annoying. For example:

So the question becomes, was it worth computing that small amount of frame N+1 or N+3?

Scenario 2: GPU is slower than Refresh Rate, VSync Off

Refresh rate: 60 Hz
GPU: 47 fps
Mouse/Keyboard responsiveness is 1-2 frames, or ~21.3 to 43 milliseconds
Effective responsiveness makes the game feel it is between 25 and 47 FPS

In this case, the GPU is ~37% slower than the screen. This means that as the GPU fills the frame buffer slower than what the screen requests and it will continuously be between frames when the display dumps the buffer contents on screen, such that the computation of the old frame and the new frame is still in the buffer.

So does this mean that for a better experience, computing frame N+1 was not needed, and N+2 should have been the focus of computation?

Scenario 3: GPU can handle the refresh rate, V -Sync On

This setting allows the GPU to synchronize to every frame. Now all elements of the system are synchronized to 60 Hz—CPU, application, GPU and display will aim for 60 Hz, but also at lower intervals (30, 20, etc.) as required.

While this produces the best visual experience with clean images, the input devices for haptic feedback are limited to the V-Sync rate. So while the GPU could enable more performance, this artificial setting is capping all input and output.

Result:

If the GPU is slower than the display or faster than the display, there is no guarantee that the frame buffer that is drawn on the display is of a complete frame. A GPU has multiple frames in its pipeline, but only few are ever displayed at high speeds, or frames are in-between when the GPU is slow. When the system is set a software limit, responsiveness decreases. Is there a way to take advantage of the increased power of systems while working with a limited refresh rate—is there a way to ignore these redundant tasks to provide a more 'immersive' experience?

LucidLogix apparently has the answer…

The answer from Lucid is Virtu MVP. Back in September 2011, Ryan gave his analysis on the principles of the solution. We are still restricted to the high level overview (due to patents) explanation as Ryan was back then. Nevertheless, it all boils down to the following image:

Situation (A) determines whether a rendering task/frame should be processed by the GPU, and situation (B) decides which frames should go to the display. (B) helps with tearing, while (A) better utilizes the GPU. Nevertheless, the GPU is doing multiple tasks—snooping to determine which frames are required, rendering the desired frame, and outputting to a display. Lucid is using hybrid systems (those with an integrated GPU and a discrete GPU) to overcome this.

Situation (B) is what Lucid calls its Virtual V-Sync, an adaptive V-Sync technology currently in Virtu. Situation (A) is an extension of this, called HyperFormance, designed to reduce input lag by only sending required work to the GPU rather than redundant tasks.

Within the hybrid system, the integrated GPU takes over two of the tasks for the GPU—snooping for required frames, and display output. This requires a system to run in i-Mode, where the display is connected to the integrated GPU. Users of Virtu on Z68 may remember this: back then it caused a 10% decrease in output FPS. This generation of drivers and tools should alleviate some of this decrease.

What this means for Joe Public

Lucid’s goal is to improve the 'immersive experience' by removing redundant rendering tasks, making the GPU synchronize with the refresh rate of the connected display and reduce input lag.

By introducing a level of middleware that intercepts rendering calls, Virtual V-Sync and HyperFormance are both tools that decide whether a frame should be rendered and then delivered to the display. However the FPS counter within a title counts frame calls, not completed frames. So as the software intercepts a call, the frame rate counter is increased, whether the frame is rendered or not. This could lead to many unrendered frames, and an artificially high FPS number, when in reality the software is merely optimizing the sequence of rendering tasks rather than increasing FPS.

If it helps the 'immersion factor' of a game (less tearing, more responsiveness), then it could be highly beneficial to gamers. Currently, to work as Lucid has intended, they have validated around 100 titles. We spoke to Lucid (see next page), and they say that the technology should work with most, if not all titles. Users will have to add programs manually to take advantage of the technology if the software is not in the list. The reason for only 100 titles being validated is that each game has to be validated with a lot of settings, on lots of different kit, making the validation matrix huge (for example, 100 games x 12 different settings x 48 different system hardware configurations = time and lots of it).

Virtu MVP causes many issues when it comes to benchmarking and comparison of systems as well. The method of telling the performance of systems apart has typically been the FPS values. With this new technology, the FPS value is almost meaningless as it counts the frames that are not rendered. This has consequences for benchmarking companies like Futuremark and overclockers who like to compare systems (Futuremark have released a statement about this). Technically all you would need to do (if we understand the software correctly) to increase your score/FPS would be to reduce the refresh rate of your monitor.

Since this article was started, we have had an opportunity to speak to Lucid regarding these technologies, and they have pointed out several usage scenarios that have perhaps been neglected in other earlier reviews regarding this technology. In the next page, we will discuss what Lucid considers ‘normal’ usage.

The Z77 Chipset Lucid’s Take on Virtu MVP and How it Should Work
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  • Zoomer - Tuesday, April 10, 2012 - link

    So when is AMD buying them out and integrating this in their gfx cards / platform? Reply
  • neo55 - Sunday, April 08, 2012 - link

    Will Z77 support two or three monitors simultaneously? Reply
  • GreenEnergy - Sunday, April 08, 2012 - link

    You mean from the Ivy Bridge IGP?

    Well depends. (Its the same btw for H77, Z75 and Z77 etc.). You need to have 2 displayport if I remember correctly. So if you got for example DVI, HDMI and DP. Then 2 screens only. If you got DVI, DP, DP then 3. Or if you daisychain the DP?
    Reply
  • dubyadubya - Sunday, April 08, 2012 - link

    Listing fan header count and layout is useless if you do not test the functionality. Do they report RPM? Can they control fan speed? Does the fan control work with Speedfan etc. or only the software from the motherboard manufacturer? Several years ago many people including myself brought this to Anandtech's attention. At the time Anandtech stated they would include this missing info which they did. Trouble is the info was only included in one or two reviews before it was dropped. When I purchase a new motherboard I want to know this info. I have spent many hours searching for this info for each new build as most manufactures do not give detailed info even in the motherboard manual.

    IMO if a fan header exists it must have full functionality. If not the header should not be on the board. Motherboard manufactures need to pull their heads out of their asses. If Anandtech reported this info in reviews and gave negative reviews on boards with poor fan support the manufacturers would get the hint.
    Reply
  • Nje - Sunday, April 08, 2012 - link

    Yeah I would love to know this, particularly if the fan headers can control 3 pin fans as well (ie vary the voltage). Reply
  • ASUSTechMKT - Monday, April 09, 2012 - link

    Primary CPU headers ( CPU and CPU OPT are fully controllable for 4 pin ) as the majority of CPU coolers are PWM for chassis headers ( 1-4 all allow for 3 pin and 4 pin fan control ). Reply
  • Zoomer - Tuesday, April 10, 2012 - link

    Asus, can they be used with speedfan or is it BIOS/Asus software only? Reply
  • ASUSTechMKT - Monday, April 09, 2012 - link

    This has been noted in the last couple of reviews. Specifically for ASUS we have spent considerable time putting quality fan controls on our boards all headers allow for 3 presets as well as min and max rotation and target temperatures. In addition with our software for this generation we offer full calibration per each header that can sense the min and max rotation and provide this information as well as sync this data to the profiles. Overall it is quite extensive make sure to check out our videos coming up which shows it in great depth. Reply
  • Arbie - Monday, April 09, 2012 - link

    @dubyadubya - Look on the bright side: at least one manufacturer (Asus) takes fans seriously, and at least one reviewer (Anandtech) is even mentionng the fact.

    I have the same wants as you do, and have made the same requests, but be reasonable. These aren't full motherboard reviews! They don't even have the boards operable, much less any hands-on time with BIOS details.

    And when they do have all that, a higher priority will be PCIe lanes and how many graphics cards can be stuffed in. That's because you can't run any modern games with only one board.

    But then they might talk a little more about the fan controls... Let's hope. Again - be glad that even one vendor is paying attention and has included some controls to be talked about.
    Reply
  • Cavalcade - Sunday, April 08, 2012 - link

    With a slightly more than passing knowledge of rendering, and having spent a fair amount of time handling input in a game engine, I'm curious as to how Lucid came to the responsiveness numbers in the chart on page 3. The concept seems valid at first glance, but the numbers strike me as pure marketing fodder as opposed to solid and testable results.

    Also, this sort of technology seems far better suited to residing in the driver layer as opposed to yet another piece of middleware for PC gamers to contend with. We're already effectively blocked from the hardware, and forced to go through third-party graphics APIs (Direct3D/OpenGL).

    Maybe it's a "you have to see it (feel it)" kind of thing, but from here you can color me skeptical.
    Reply

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