This multi-graphics parallel processing technology, nVIDIA called SLi, ATi called crossfire, is like a fat man doing exercise, we call it slimming, and TV calls it slimming.
Establishing SLI system in actual combat
As early as 2004, nVIDIA introduced Geforce 6800Ultra with the core code of NV40. The performance of NV40 has almost doubled compared with the previous generation, which has brought nVIDIA back to the performance throne for a long time. But ATi obviously didn't expect the performance of NV40 to be so powerful. Radium Dragon X800 XT, the core code R420, rushed to fight, and as a result, its performance was slightly better than Geforce 6800Ultra. The flagship product is a symbol of a company's technology, and the king of performance is the proof of technological leadership. So ATi further upgraded the frequency of Radium Dragon X800XT, and introduced the monster radiator and ATI Radium Dragon X850 XT PE with ultra-high clock frequency, which took the throne of the strongest game card. Strangely, NVIDIA seems to turn a blind eye to this and announced the cancellation of the development plan of NV48. On June 29th, on the occasion of the third anniversary of NVIDIA's acquisition of 3DFX, NVIDIA officially announced that it would use SLI technology on NV4X graphics cards, and use SLI system which can work on two graphics cards at the same time and improve the basic performance against ATi.
NVIDIA officially claims that the SLI system can provide 1.9 times the performance of a single card. Considering the amazing performance of a single Geforce 6800Ultra, you can get the performance of a single Geforce 6800Ultra1.9 times as long as you buy two GeForce 6800 Ultras. No wonder fans all over the world flock to the SLI system.
What is the SLI system?
SLI (Extensible Link Interface) allows multiple graphics chips to work at the same time to obtain higher performance. Senior players should remember that 3DFX first introduced VOODOO2 SLI, which connected two VOODOO2 of the same brand through a dedicated data cable, providing the top 3DF performance at that time. Although the two graphics cards work at the same time, the SLI technology introduced by NVIDIA is actually different from that of 3DFX. SLI of VOODOO2 is responsible for rendering even and odd frames through two graphics cards, which reduces the burden of graphics cards and improves performance. SLI technology in NVIDIA is different.
When two graphics cards are connected by an external bridge connector, the driver can automatically recognize the configuration and enter the SLI multi-GPU mode. In SLI multi-GPU mode, the driver configures the two graphics cards as an independent device: that is, all graphics processing programs regard the two graphics chips as an independent logical device. NVIDIA's driver plays an important role in keeping the symmetry between light and shade. It considers the workload and makes two key decisions: 1) decides the shading method, and 2) decides the workload sharing between two GPUs according to the shading method.
NVIDIA supports two main shading methods: alternating frame rendering (AFR) and split frame rendering (SFR). As the name implies, AFR allows each GPU to color separate frames (for example, GPU 1 colors all odd frames, while GPU 2 colors all even frames). As long as each frame is independent, AFR is the most efficient, because all rendering including vertex-by-vertex, rasterization and pixel-by-pixel should be evenly distributed in the graphics. We often see 3Dmark03 running in AFR mode, with a maximum of 87. SFR distributes the shading of a single frame to two GPUs. NVIDIA drivers are usually not sure whether to use AFR or SFR. NVIDIA software engineers have configured most of 100 popular games, created configuration files for each game, and decided whether to use AFR or SFR mode by default in each game. As long as there is no dependency between frames, NVIDIA's driver defaults to AFR.
To run SLI, you need to build a platform supporting SLI and a SLI system. You need: 1, a motherboard supporting SLI; 2. Two nVIDIA SLI certified graphics cards are required; 3.windows XP operating system.
Although nForce4 SLI is not the first chipset to support SLI, Intel's Tumwater(E7525) motherboard belongs to workstation/server level, so at present, home users usually use the motherboard of nForce4 SLI chipset to set up SLI system. As far as the current situation is concerned, the prospect of SLI is bright. NVIDIA is ready to launch nForce 5 Intel chipset supporting SLI, and VIA and SIS will also launch so-called dual PCI GFX technology, just waiting for NVIDIA to nod. Therefore, in the current situation, to build a SLI platform, using nForce4 SLI chipset is the choice of most players. The high-speed digital interface of the motherboard is used to connect two graphics cards. Without its help, the SLI system cannot be formed.
As for the graphics card, it must pass the SLI certification in NVIDIA, and the SLI interface on PCB is the best illustration. Pay attention to when purchasing graphics cards. According to nVIDIA, two graphics cards need the same brand and model to start the SLI function. As far as the current market situation is concerned, nVIDIA divides the high-end Geforce 6800Ultra, the middle-end Geforce 6800GT and Geforce 6800 GT, and the low-end Geforce 6600GT3 into three grades. The graphics card performance of Geforce 6600GT SLI system is quite amazing, and it can achieve 4-screen output. Such devices are quite lethal to consumers who want to configure low-end graphics workstations.
Finally, make sure that the power supply in your hand can provide enough current. According to the official explanation of NVIDIA, the SLI system built by high-end Geforce 6800Ultra needs 500W~550W power wattage. I believe everyone knows the power consumption of Geforce 6800Ultra, but now there are two GeForce 6800 Ultras, and the power consumption is naturally great.
Establishing SLI system in actual combat;
Let's build the SLI system in actual combat. The motherboard adopts ASUS A8N-SLI Luxe motherboard based on nForce4 SLI chipset, and the Socket 939 interface of ASUS A8N-SLI Deluxe Edition supports AMD 939 Socket Athlon 64 FX/Athlon 64 processor. The frequency of the bus reaches 2000 MT/s, there are four DIMM slots, and it supports dual-channel DDR400 memory, which can be expanded to 4GB at most. It is also equipped with three PCI slots, two PCI Express x 16 slots and PCI Express x 1 slot, which supports the latest SATA2 specification and provides a transmission speed of up to 300 MB/ s.
Asustek's nForce4 SLI motherboard is characterized by two PCI Express x 16 slots that are more open than other motherboards. The advantage of this is that when setting up the SLI system, the space between the two graphics cards is much larger, which is more conducive to the heat dissipation of the graphics cards.
In terms of graphics cards, the evaluation room has prepared two sets of graphics card schemes, namely, the flagship Geforce 6800Ultra SLI and Geforce 6600GT SLI for the mid-market.
Before installing the graphics card on the motherboard, first make sure that the installation direction of the EZ selector daughter card of the motherboard is dual graphics card mode (supporting dual graphics cards). If the card is inserted incorrectly and one side of the single graphics card is installed on the motherboard, SLI mode will not be enabled.
After confirming that the EZ selector daughter card is inserted into the slot, you can insert two graphics cards into two PCI Express x 16 slots. After confirming that the two graphics cards are tightly inserted into the PCI Express x 16 slot, carefully install the SLI bridge daughter card on the SLI interfaces of the two graphics cards, as shown in the following figure, and confirm that the SLI bridge daughter card has been tightly installed. It should be noted here that the installation of the SLI bridge daughter card cannot go wrong, otherwise the SLI system cannot be started. The correct installation direction is as follows:
Then, a set of 4pin ATX power interfaces will be installed on the EZ-plug interface of the motherboard. If you don't connect this 4pin power interface, the system will be unstable and the red warning light on the motherboard will light up.
In addition, it is also important to confirm whether the electricity used is enough. The power of two Geforce 6800Ultra is beyond the ordinary power supply. Recently, the famous computer hardware website HKPEC announced the test of the SLI system, and the test conclusion is that 300W can withstand the Geforce 6800Ultra SLI system. However, there is a premise that the power supply of 12V of the tested 300W power supply must reach the level above 25A, and the author started to test the Dell 400W disassembled power supply. Because the output cut-off of 12V is too low, the Geforce 6800Ultra SLI system cannot be called out. After replacing the 350W power supply of Hangjia Teana Voice, the test can continue. At this point, the hardware part is over.
Then there is the software part, and the BIOS setting is of course indispensable. The SLI mode item in the BIOS is set to automatic, which allows the BIOS to automatically detect the setting of the EZ selector daughter card on the motherboard. Of course, choosing the SLI option can also ensure that the graphics card runs in SLI mode.
After entering the system to install the driver, the system will automatically prompt the user to open SLI mode in the graphics card driver option. After checking the box in the figure below, the SLI system is considered to be completed. It is worth noting that when establishing SLI system, we should pay attention to the selection of driver version and install the driver version supporting SLI technology.