nForce4 SLI Intel Edition - Prev Following its great success with the Athlon XP and then the Athlon 64 platforms, NVIDIA is now attacking the Pentium 4 market with the Intel version of the nForce 4 SLI. What is this chipset worth compared to the i925XE ? With its arrival on the chipset market with AMD processors in 2001, NVIDIA has slowly made its way to the top of this market, this is due more particularly to the nForce 2 and nForce 4, which have provided better performances and functionalities than the competition. Despite ongoing rumors, NVIDIA had never before attempted to attack the chipset market for Pentium 4, outrageously dominated by Intel. This wasn’t apparently due to a technical problem but more to a financial one. NVIDIA didn’t want to pay too much for the license authorizing the release of such chipsets. It was only last November 19, 2004, that NVIDIA and Intel signed a licensing agreement to allow NVIDIA the possibility of releasing chipsets for Intel platforms. nForce 4 SLI Intel Edition Initially NVIDIA decided to announce only one chipset for Intel platform, the nForce 4 SLI. Intended for high-end computers, it will be followed by other, cheaper, versions during the year to come, as well as laptop, servers/workstation declinations. Unlike its equivalent for AMD, the nForce 4 SLI Intel Edition is made up of two distinctive chips. - The SPP, 61 millions of 130 nm transistors - The MCP, 21 millions of 150 nm transistors This separation is due to the fact that with the Athlon 64, the memory controller is included in the processor whereas with Intel’s platforms, the chipset still has to deal with this functionality. This explains why it is more complex. The SPP, which plays the part of Northbridge, supports the processor bus, memory bus and PCI-Express bus. As a bus processor it supports the Pentium 4 QDR with frequencies between 100 and 266 MHz (FSB400-FSB1066). It supports single and dual core processors. The only limitation for the second case is that the motherboard design must be adapted (our reference motherboard wasn’t). The memory controller is, in fact, made up of two 64 bits controllers. It allows the nForce 4 SLI to be fairly flexible and provides a similar dual channel even with non-symmetrical memory channels (of course performances are optimum only when they are symmetrical). These two controllers work together in 128 bits and support not only the DDR-2, but also the DDR-2 400, 533 or 667, in FSB800 and in FSB1067 (via FSB:DDR ratios of 4:3, 1:1, 4:5, 3:4 and 3:5). As these FSB respectively provide a possibility of reaching 6.4 and 8.5 GB /s of bandwidth, the compatibility with the DDR2-667 seems a little bit compromised at first sight, since it allows a 10.6 GB /s theoretical bandwidth. In order to support this DDR2-667 mode, even with 4 memory modules without using 2T Timing, NVIDIA has decided to integrate a specific address bus for each DIMM. The data bus is still shared between the two DIMM of each channel. So in the end, the nForce 4 is able to support a grand total of 4 DIMM of 4 GB, two per channel. Even though Intel’s pre-fetching system works really well, NVIDIA also decided to integrate the DASP 3.0 version in the nForce 4. Its job is to guess, whenever possible, which data will be necessary for the processor in order to pre-load them. Finally, the memory controller integrates the QuickSync technology, whose objective is to not reduce performances when the processor bus and memory bus are using asynchronous frequencies. This type of technology is, of course, strongly recommended since Intel’s chipset deals with this asynchronism without any problems, unlike the nForce 2 whose performances dropped with this type of configuration. The last, but not the least point, supported by the nForce 4 SLI Intel Edition STP is the PCI Express bus. It supports a total of 20 PCI Express lanes and a maximum of 4 peripherals. So it is possible, for example, to have one PCI Express x16 slot and 3 PCI Express x1, as well as the SLI, two PCI Express x16 slots cabled in x8 two PCI Express x1. These two x16 slots will accept two PCI Express graphic cards, which would also be able to work independently for multi-displays, or together in SLI, if they feature this function.