Little more than two years have passed since NVDIA first introduced their SLI technology. Short for Scalable Link Interface, SLI is the first solution to be able to connect two PCI-Express video cards based on the same GPU in a way that they will operate parallel to each other. This type of approach allows, at least on paper, to have an increase in performance of up to double what you would normally have with a single video card. In the first months of SLI’s release, it potential was limited by driver problems and other software errors.

However, forwarding two years into the future and with the release of several new driver versions from NVIDIA, SLI technology has really matured as a whole. Stability has been greatly improved and support has been added to an increasing list of games. SLI support has also been made more accessible to the general public with the release of average and entry level video cards that support the technology. Currently, SLI will even be made available on NVIDIA’s most budget level class of GeForce 7 video cards, the 7100 GS, thus making it a solution that is affordable and available to a vast amount of computer users.

At this moment, SLI and Crossfire technologies can be considered the first full phase of maturity for a broader category: multiple GPUs. The next phase is for more than two video cards being linked up to each other in an effort to, yet again, increase performance. As NVIDIA was first to reach the market with a dual video card solution, they have yet again been able to beat ATI in announcing a solution that utilizes more than two GPUs. The technology is, none other than, Quad SLI (the name isn’t very original). Quad SLI has four GPUs operating parallel to each other, theoretically doubling the performance in respect to an SLI setup.

Quad SLI on display by NVIDIA at CES 2006 in Las Vegas

The first public demonstration of this technology from NVIDIA happened January 2006 at the Consumers Electronics Show (CES) of Las Vegas. From that moment on, NVIDIA displayed many more glimpses of Quad SLI at various events, however, its performance at that time was not an accurate example of its true potential due to early driver problems. Initially, Quad SLI was going to be available only in systems of partner OEMs, and NVIDIA, in fact, allowed the technology to be used, exclusively at first, in Dell’s XP 600 Renegade. The XPS Renegade was made available for purchase in March 2006 at the price of $10,000. The system came locked and loaded with a pair of custom NVIDIA 7900GTX 512 MB cards. As can be expected, the systems were extremely limited and available to a very small portion of the public because of their price. Although the XPS Renegade looked cool, we personally preferred going for a solution that wouldn’t have required us to sell our car.

The 7950 GX2 was released for retail June 5, 2006. The 7950 GX2 replaced its predecessor the 7900 GX2, which suffered from many problems including layout, size, noise, power consumption, and price. With the release of the 7950 GX2, much of these problems have been addressed and changed. The PCB has been taken down to the size of a regular 7900 GTX and now only a single PCIe power connector is required. Although the GeForce 7950 GTX was compatible with Quad SLI on release, users could not take advantage of this feature until the release of the Forceware 91.45 drivers. With the release of the new drivers, this technology has been made officially available to customers who are passionate enough to want to assemble a Quad SLI system alone.

Quad SLI, as we will see in the course of this article, is a technology that traces its roots back to SLI. At the moment, driver compatibility and DirectX 9 are the main limiting factors in addition to cost and availability.

sistema Quad SLI con schede GeForce 7950 GX2

In the course of this analysis we will benchmark our Quad SLI setup that utilizes two 7950 GX2 (four GPUs) video cards against a system armed with two GeForce 7900 GTs running in SLI, a system with two ATI Radeon X1900XTX video cards running in Crossfire and one system with an ATI Radeon X1950XTX video card also running in Crossfire.

The following table displays the technical characteristics of the four main top of the line video cards from ATI and NVIDIA next to their specifications when they are running in Crossfire or SLI mode.

The first NVIDIA solution we will be looking at today is the GeForce 7950 GX2. The 7950 GX2 comes equipped with two GPUs, thus making it have a total of four under SLI, coining the term Quad SLI. The cards each have two G71 GPUs, the same GPUs are also on the GeForce 7900 GTX cards. The 7950 GX2, however, is set at a lower clock. Technically two boards screwed together, two GPUs of the 7950 GX2 are connected to each other using an on-board two way communications system. From there they both connect to the motherboard using only one PCI-E 16x slot.

Quad SLI systems are basically systems configured to run with two 7950 GX2 boards, thus adding up to a total of four GPUs. Combined together, Quad SLI systems hold the most graphical power consumers can get in their systems currently. This, however, does not necessarily mean that it will have the highest absolute performance.

Moving on to ATI, we see that their solution, Crossfire, has a different approach to having multiple GPUs running parallel to each other. ATI’s solution requires users to have a Mastercard and an ordinary slave card in order to enable Crossfire. Unfortunately at the moment there is no Mastercard for the X1900XTX, and so we had to revert back to using an X1900XT Mastercard paired with a (slave) X1900XTX. Since the Crossfire architecture always require the Core/Memory frequencies of the two video cards involved to be equal to each other, our X1900XTX slave video card was forced to scale its core and memory clock to that of the X1900XT (this happens automatically). As a direct consequence of this we cannot use the full potential of the X1900XTX and must settle for 625 MHz Core and 1,450 MHz memory.

SLI System with 2 GeForce 7900 GTX Video Cards

Our two GeForce systems both use bridges, which are mechanical connectors, for the transmission of data between the multiple GPUs. Every video card in its turn is connected to a PCI-Express 16x slot on the motherboard.

Crossfire system with a Radeon X1950XTX Video Card

As can be seen, our Crossfire video cards connect externally by using a special cable that comes with the Mastercard.

Before moving further into this article, we would like to give a quick and painless introduction to the various resolutions that are available for use with these video cards. In our opinion, what would be the use of Multi-GPU technologies if we didn’t push them to the max by using the highest resolutions possible? As is pretty evident from how high-end they are, and also from their price, multi-GPU systems naturally allow, in addition to AA and AF being enabled, the use of very high resolutions.

The diagram above compares various resolution levels. As can be seen, in relationship to the standard 4:3 ratio, the widescreen 16:10 ratio can really create a much more engaging experience inside a typical action game. Because of the larger horizontal length, widescreen aspect ratios can provide a much more complete view in 3D games.

4:3 standard Display

Wide Display

To show a little bit more comparison between widescreen and standard 4:3, the two screenshots show just how much more engaging a 3D game becomes when using wider resolutions. For more information on gaming with wide screens resolutions, we suggest you to visit Widescreengamingforum, an excellent source of information in this matter.

The total number of pixels that a video card must process depends on the resolution used. The larger the resolution is the larger the complexity and size of the operations to which the video card will be subjected to:

• 1280x1024: 1.31 Mpixel
• 1600x1200: 1.92 Mpixel
• 1920x1080: 2.07 Mpixel
• 1920x1200: 2.3 Mpixel
• 2048x1536: 3.14 Mpixel
• 2560x1600: 4.09 Mpixel

From the above, we hope that you can more easily understand why managing a resolution such of 2560x1600 pixels, at the present moment the highest resolution the largest 30inch TFT screens available on the market can handle, would be such a daunting task for any video card. The 2560x1600 resolution is pretty much double, in terms of Mpixels, the resolution of 1920x1080 which is the necessary resolution to display HD video.

In order to construct a Quad SLI test system that any of our readers could build, we chose our components carefully and only bought parts that are available for retail. Our motherboard, the Asus M2N32-SLI Deluxe, is a Socket AM2 based motherboard that comes with the NVIDIA nForce 590 SLI chipset. We used exactly 2 Gigabytes of DDR2-800 memory along with two Point of View 7950 GX2 video cards.

The two Point of View cards are identical to the NVIDIA reference card along with all other GeForce 7950 GX2 solutions available on the market. The product conforms exactly to NVIDIA’s recommended settings and comes with a 500 MHz clock for the GPU and a 1.2 GHz clock for the video memory. Each 7950 GX2 has 1024MB Mbytes (512 Mbytes for each core). It is no mystery that all GeForce 7950 GX2 cards are constructed in the same factory, and are supplied from NVIDIA to several partners who sell them as finished products.

After installing the video cards, it is noticeable that they are relatively close to each other. The direct consequence is that during operation the video cards generate a remarkable amount of heat, so we suggest making sure there is an adequate cooling system installed in your system in order to avoid overheating problems.

The video cards come with a copy of Prince of Persia: The Two Thrones on DVD, a CD that contains drivers, a DVI to VGA adaptor, an external box for management of video signals with connections for component, composite video and S-Video, a Molex to 6 pin PCIe connector, and a video card manual.

NVIDIA requires the use of an additional power source for their 7950 GX2 cards in order to guarantee operating stability while connected in Quad SLI. In the course of the tests we used a 620 Watt Enermax PSU that is part of their Liberty series. Using

The GeForce 7950 GX2 is mounted with two G71 graphics processors. Each GPU comes equipped with 8 vertex shader units (VSU), 24 pixel shader units (PSU), 24 texture mapping units (TMU), and a 256 bit memory bus. Therefore, combined these two GPUs have 16 VSU, 48 PSU, 48 TMU and a 512 bit memory bus.

The distribution of the work load between the two GPUs follows in the footsteps of how SLI technology does so. To be honest, there isn’t much use to buy a GeForce 7950 GX2 unless you intend to buy another one and use it for Quad SLI. If you only have a single GeForce 7950 GX2, the card does not do much other than implement SLI technology on a single video card, which until now has only been used to make two GPUs on two different video cards work simultaneously with each other.

The real innovation introduced by the GeForce 7950 GX2 is that it is the first mass produced video card to use a PCI-E switch. The PCI-Express switch between the two PCBs interconnects the two video cards and allows them to communicate with each other using the switch’s 48-lanes. The switch connects 16 PCI-Express lanes to each GPU and the remaining 16 lanes are used to interface with the motherboard’s PCI-Express connector.

A Quad SLI configuration is obtained through the use of two GeForce 7950 GX2 cards, totaling 4 GPUs operating simultaneously with each other.

So what are the modes with which NVIDIA operates SLI technology? Two are techniques which were adopted from the first implementation of SLI from the time of the GeForce 6800 cards:

• Alternate Frame Rendering (AFR): in AFR the CPU and GPU process each frame at the same time before going on to the next frame. The frames rotate between video cards, thus improving performance in non-CPU limited situations.
• Split Frame Rendering (SFR): with this technique the rendering of every frame is divided between the two cards. The percentage of rendering can be 50-50, but can also be done dynamically between the two cards depending on the game that is being used.

The availability of four GPUs to render frames makes the picture fairly more complex for NVIDIA. In Quad SLI, NVIDIA uses Alternate Frame Rendering, Split Frame Rendering, and have also added an exclusive mode that that uses both of the above modes simultaneously called &ld

As we emphasized earlier in the article, the significant power that a Quad SLI has allows for higher resolutions and also offers higher image quality.

NVIDIA has introduced three new modes of AA called SLI Anti-aliasing: 8x SLI AA, 16x SLI AA and 32xS SLI AA. These modes improve the total image quality of rendered scenes, and are for this reason, where possible in our testing, turned on.

With the introduction of ForceWare 90 Series, NVIDIA’s new control panel allows users to manually set their preferred level of anisotropic filtering and Anti-Aliasing. Even if it is not supported by the specific game, you can force the settings on the game.

Anisotropic Filtering can be set at 16x

anti aliasing through the NVIDIA control panel allows SLI32x to be enabled with Quad SLI

The rendering mode can be forced upon the game or decided automatically through the drivers

Quad SLI technology can be enabled or disabled

ATI Driver Panel

In order for us to build a system to test SLI, Quad SLI and Crossfire technologies, it was necessary for us to build two distinguished test systems. SLI demands use of platforms based on NVIDIA chipsets, while Crossfire can be used with solutions based on ATI or Intel 975X chipsets. We opted on an nForce 590 SLI motherboard for the SLI systems and an ATI Crossfire Xpress 3200 motherboard for the ATI Crossfire video cards. We combined the motherboards with an AMD Athlon 64 FX62 and 2 Gigabytes of DDR2-800 system memory.

For more details:

All tests were done starting at a resolution of 1280x1024 pixels and tested up to 2048x1536 pixels. Unfortunately, it was not possible for us to use a resolution of 2560x1600 pixels for the lack of a display that would be able to support the resolution. At the present moment there are very few displays that support 2560x1600. Because these solutions are particularly expensive, availability on the market of these displays is rather thin.

The games we will be testing with are:

• Far Cry
• Splinter Cell: Chaos Theory
• Doom 3
• Half-Life 2 Lost Coast
• Serious Sam 2
• Call Of Duty 2
• F.E.A.R.
• The Elder Scrolls IV: Oblivion
• X3: Reunion
• Prey

Asus M2N32-SLI Deluxe

The ECS KA3 MVP: Socket AM2, chipset ATI Crossfire Xpress 3200

F.E.A.R. is one of the game titles that NVIDIA themselves used to show the potentials of Quad SLI. It was used to demonstrate their “Extreme HD Experience” for a number of reasons, one of them because F.E.A.R. can be pumped up to a resolution of 2560x1600 pixels.

It is no surprise to see the Quad SLI system leading the pack with 8xAA and 16xAF enabled. At the resolution of 2048x1536 pixels, the margin of advantage over the Radeon X1950XTX Crossfire is little more than 11%. At the same resolution, in regards to the GeForce 7900 GTX SLI System, Quad SLI holds around a 40% advantage.

The above benchmarks might be a bit harder to understand, so we’ll briefly explain what the graphs actually represent. All values on the above graph are percents. The values compare the performance we received using AA set at 8x against AA set at 4x. So, for example, the above graph tells us we received 62.16% of the performance, using 8xAA, that we would have gotten using 4xAA. All tests were run with AA set at 8x.

The results we obtained are evidence to a sure margin of advantage for the GeForce 7950 GX2 Quad SLI Solution. The lack of performance diminishment from switching 4x AA to 8x AA shows us the excellent scalability of Quad SLI and the power of the setup.

With Soft Shadows enabled, the performance offered by the cards tested begins to become much more similar. In both cases the GeForce architecture performs better than the Radeon one. The GeForce 7950 GX2 also always succeeds to best all Radeon solutions by a considerable margin when tested at higher resolutions.

Far Cry is a title that awards the use of multiple GPUs, as the benchmarks are evidence to. With AA 4x and anisotropic filtering set at 16x with the resolution at 2048x1560 pixels, the significant workload on the Quad SLI setup does not allow the Quad SLI configuration to keep a major advantage over the two ATI Crossfire systems.

All values in % for graph directly above

The picture changes here when AA 8x is enabled: the GeForce 7950 GX2 Quad SLI Solution distances itself in terms of performance from the two Crossfire solutions. The benchmarks also present a much more interesting topic on the analysis of performance scalability. Once more, we see strong performance displayed by the GeForce 7950 GX2 and see very little performance lost when passing from 4xAA to 8xAA.

The demo version of Prey shows a scene similar, in terms of performance, to how well the 7950 GX2 performed in F.E.A.R. With anti aliasing at 4x and anisotropic filtering at 16x, the Quad SLI configuration succeeds to take the lead in performance over other competitors. The advantage margin for the 7950 GX2 increases even further when anti aliasing is increased to 8x.

All values of graph directly above in %

In this case the impact on the frames passing from AA 4x to AA 8x is much greater. System performance for the GeForce 7950 GX2 Quad SLI system is only 53.64% of what the FPS would be at 4xAA running at a resolution of 2048x1536.

In order to further investigate the impact anti-aliasing has on system performance, we ran the following tests using Prey. All tests were done with anisotropic filtering set at 16x.

As we increase anti-aliasing, the FPS of the system diminishes with a sure course until the system is struggling with 32x SLI AA. Setting AA to 8x SLI, a substantial and obvious halving of performance is recorded using the resolution of 2048x1536 pixel where the FPS goes from 105.8 to 56.7. Increasing anti-aliasing from 8x AA SLI continues to reduce performance in proportion. The performance of the system always seems to halve itself.

It is interesting to note the drop of frames per second from 32.2 to 9.1 when SLI AA 32x is enabled. The values offered 32x SLI AA are pretty much unplayable. NVIDIA indicates, in their own datasheet, that SLI AA 16x and 32x performance is evidence to the extensive power of a Quad SLI system. From our tests, it is obvious a Quad SLI system is brought to its knees by high resolutions coupled with high anti-aliasing.

A similar course in regards to the Quad SLI system was followed by the GeForce system 7900 GTX SLI system. After 8x SLI AA is enabled, performance is nearly always halved as resolution levels are increased.

In the above tests, both ATI Crossfire architectures display performances that are very similar to each other. It is obvious that as the anti aliasing level goes over 8x AA, there seems to be no performance difference between the preceding level of anti aliasing and the current level. In truth, the video driver is probably forcing use of the previous AA mode because of the lack of sufficient video memory.

In Splinter Cell, the Quad SLI 7950 GX2 takes a step back from leading the pack and instead settles for a humbling fifth place in both of the tests we ran. In both tests, ATI’s Crossfire solutions were faster and delivered the best performance, and immediately after them came the 7900 GTX SLI. Ironically, a single 7950 GX2 card beat the Quad SLI setup.

Half-Life 2 is a title that has historically always rewarded ATI architectures. From the above tests, the victor should best be left up to you to decide. In two out of the three tests we ran, Quad SLI bested all other solutions; however, the performances offered by the video cards were very close to each other. With anti aliasing set at 8x and running the game at a resolution of 2048x1536 pixel, the Quad SLI setup leaves the Radeon X1950XTX Crossfire system behind by approximately 11%

All values above in %

This is another scaling test we ran. An analysis of the percent of performance changing from anti aliasing 4x to 8x shows almost perfect scalability for Quad SLI. The frames remain nearly perfectly the same at the resolution of 2048x1536 pixels.

Although Doom 3 has been on the market for quite some time now and its engine has been used in other test titles of ours, Doom 3 continues to remain a classic game in the video card scene. In the tests we only used the resolutions of 1280x1024 and 1600x1200 pixels, coupling the resolutions with 4x anti aliasing and 8x anisotropic filtering. From the benchmarks we ran, it is evident that the cards were very close together in terms of performance.

In Call of Duty 2, Quad SLI seems to struggle quite a lot. In spite of the GeForce 7950 GX2 having been the fastest out of all single cards, the GeForce 7950 GX2 under Quad SLI does not have impressive performance at all in this title.

Again, despite the GeForce 7950 GX2 being the fastest single slot solution, with 4x anti aliasing and 16x anisotropic filtering, Quad SLI performed worse out of all four multiple GPU solutions tested. Quad SLI was also outdone in terms of performance by the GeForce 7900 GTX SLI system.

Turning anti aliasing up to 8x, Quad SLI once again conquers first place with 10% better performance over the Radeon X1950XTX Crossfire solution.

Going from 4x to 8x anti aliasing in X3: Reunion, the GeForce 7950 GX2 Quad SLI solution maintains nearly the exact FPS that it had with anti aliasing at 4x. The results can be simply explained by saying that only with 8x AA can the power of a Quad SLI system, with this title, be taken advantage of.

In Serious Sam 2, with anti aliasing set at 4x and anisotropic filtering at 16x, the GeForce 7950 GX2 shows itself to be the fastest single slot solution. However, going over to a Quad SLI configuration, performance is not properly scaled and we see very inferior performance compared to the other Crossfire and SLI solutions.

Placing anti aliasing on 8x, the performance for the Quad SLI system improves considerably. It is able to take the lead and outdo the Radeon X1950XTX Crossfire by approximately 29% at the resolution of 2048x1536 pixels. The performance shown by the Quad SLI system is confirmed from the analysis of the scalability graph directly above. The Quad SLI system lost very little FPS moving from 4x anti aliasing to 8x anti aliasing.

With HDR, Quad SLI performs very similar to the first tests run on this page. Running Serious Sam 2 in full HDR along with anisotropic filtering at 16x greatly diminished the Quad SLI system’s performance. Despite this, the 7950 GX2 was the fastest single slot solution yet again.

Oblivion does not work particularly well with Quad SLI. In spite of that, the 7950 GX2 is once more the fastest single slot solution.

The Radeon X1950XTX Crossfire system, although always ahead of the Quad SLI machine, isn’t able to pull ahead of the GeForce 7900 GTX SLI system.

Using several test resolutions, in this page we will analyze the percent of FPS increase that occurs when going from a configuration using one video card to a configuration using two video cards. The testing was run using anti aliasing set at 4x and anisotropic filtering at 16x.

With this first group of tests, it is clear that Crossfire and SLI scale performance very well when going from the use of one card to two cards. Quad SLI, on the other hand, sees a lot less gains in performance. In some cases we even saw decrements in performance. This is a result of DirectX 9 and its clear issues with AFR mode. Because of DirectX 9, the Quad SLI setup is forced to instead use a traditional SLI mode, using therefore only one GeForce 7950 GX2 video card with the two GPUs connected in SLI.

This group of games shows the percent of performance increase beginning to become roughly the same among the tested video cards. The 7950 GX2 Quad SLI shows some interesting performance increases in the above tests. In particular, when Prey was run at a resolution of 2048x1536, we see a massive increase in performance of 82% when adding a second GeForce card 7950 GX2. We believe the main reason the 7950 GX2 performed so well in scaling performance from one to two video cards is because Prey’s engine uses OpenGL. Unlike DirectX 9 which has problems with AFR mode, OpenGL does not.

The main point of this article was to analyze the performance of a Quad SLI system while benchmarking it against other Multi-GPU solutions from NVIDIA and ATI. All of the video cards we chose for testing offered the best performance for their class. The speed at which they rendered scenes and the image quality they offered were unbeaten by other video cards. In addition, these video cards also allowed for resolutions to be set at very high levels.

The tests that were run at a resolution of 1280x1024, the native size for most 19 inch TFT screens, shows us that that a Quad SLI system has very little chance to be fully being taken advantage of at lower resolutions. It is necessary for a configuration of this type to be used at higher resolutions with AA and AF being turned on in order to show its true potential.

The first element of the Quad SLI system that is necessary to discuss is the cost. Before actually discussing the price involved for buying two GeForce 7950 GX2 video cards, it is important to discuss the price of the display. In order to take advantage of Quad SLI, it is necessary to have a monitor that can actually support high resolutions. At the time of this article’s writing, two monitors that fully support a resolution of 2560x1600 pixels are the Dell UltraSharp 3007WFP and the Apple M9179LL/A. Both of these displays retail for $1,709.10 and $1,999.00 respectively. Combined with the cost of all 2 GeForce 7950 GX2 video cards, it is easy to see why a Quad SLI setup isn’t for the everyday user. In fact, it is for users that go a bit beyond even “hard core.”

The price you would spend on a pair of GeForce 7950 GX2 video isn’t far behind the costs for the display. Currently, a single 7950 GX2 card is retailing for around $500. For a Quad SLI setup, it would naturally be required for you to buy two 7950 GX2 cards, coming in for a total cost of around $1,000. Add this to the cost of a high end processor (you don’t want your performance to be CPU limited) in addition to the cost of a high-end power supply unit, and you can see why a budget with a lot of overhead is considered necessary to build this kind of system.

If you are considering purchasing a Quad SLI system, you might also want to put into consideration that DirectX 9 cannot fully take advantage of Quad SLI. DirectX 9, at the moment, hinders performance by not supporting queuing of enough back-buffers when working in AFR mode. This is a serious limitation to Quad SLI’s and doesn’t allow us to fully exploit it power. As can be seen in our tests, the 7950 GX2 performed the best out of all single slot solutions nearly every time when being tested against other single slot video cards. Despite this, in the section dedicated to scaling performance from one to two video cards, our results showed that with many titles Quad SLI was not able to scale performance as well as the other SLI and Crossfire configurations. It is not possible, at least at the present moment, to bypass the performance limiting problem DirectX 9 places us in. For now, we will have to wait until Microsoft releases DirectX 10 in order to fix this issue. At that time, NVIDIA’s G80 GPUs, and possibly a G80 Quad SLI solution, will most likely already be available on the market.

At this early stage of its release, Quad SLI seems to be suffering from the same limitations that plagued SLI when it first debuted. As can be expected, we are still waiting for Quad SLI drivers to mature. At the moment, driver problems often have Quad SLI performing slower than other SLI or Crossfire configurations. In time, optimizations to the drivers’ code will most likely allow us to take much more advantage of the presence of four GPUs. Also, when Quad SLI is fully compatible with more games, we should begin seeing it scale performance similar to how it did with Prey in many more situations.

Quad SLI is an excellent technological demonstration from NVIDIA. However, because the drivers are still at a very early stage and because DirectX 9’s limitations on its performance, we are not able to presently take full advantage of the theoretical performance a system with four GPUs would have. We believe that when the G80 architecture debuts, we will see Quad SLI technology undergo a large improvement. For the moment, however, in consideration to the extremely high cost of building a Quad SLI system and also because the release of the G80 is very near to us now, we see it as very difficult to actually advise you to purchase a Quad SLI system right now.

We believe that further optimizations to Quad SLI’s driver code and the release of DirectX 10 will greatly increase the performance and value of Quad SLI. Quad SLI is a technology that has a lot of potential and although it doesn’t currently offer enough performance to justify its cost, in the coming months we will most likely see many improvements be made to the technology.