We are now going to be talking about the Nvidia 790i and what kind of power supply you’re going to need for a system like this. The cream of the crop here is the EVGA nForce 790i Ultra Tri-SLI motherboard and it has everything you can imagine on it. It’s got all the standard nForce7 features which we haven’t covered much of. PCI Express 2.0 was added on the nForce7 as opposed to the nForce6 which uses PCI Express 1.0. You get double the bandwidth with PCI-E 2.0 and support for the 45nm quad core CPUs which were not supported on the 680i. This is included on all the nForce7 boards. You also have support for ESA, which is the Enthusiast System Architecture. It is a system health monitor that checks your temperatures and fan speeds. For full support you do need a compatible computer case, a power supply, and a CPU cooler that all support the ESA technology. These would include products such as the CoolIT Freezone Elite and the SilverStone TJ10.
You’ve got one more expansion slot on the 790i and it is a PCI Express x1 connector. The reason for that is if you actually had 3 graphics cards on the 780i, you’d have no available expansion slots remaining unless you’re using cards designed for water cooling. As for other features, a big one is support for DDR3. The extreme overclockers and hardcore gamers are switching to DDR3 and the 790i is the only SLI platform that supports it. The 790i has all the other features of the other boards, but also has PCI Express 2.0, Tri-SLI, and DDR3 support up to speeds of 2000MHz. Be warned though, that speed is only supported on certain modules so do select your memory carefully. The 790i also has eSATA at the back I/O panel which means you can plug an external SATA hard drive into it. There is coaxial digital sound output at the back, and one more internal SATA port than the 780i board. So it has coaxial and digital optical output, where as the 780i and 750i only have digital optical. There is also a beefier north bridge cooler on the 790i. These are the main differences between the boards.
So if you are running three graphics cards, a high powered motherboard and CPU, you’re going to need a serious power supply to boot. The Corsair HX1000W Modular Power Supply is perfect for use with these boards and is the only kilo watt power supply to be certified by Nvidia for use with the Tri-SLI technology. It is cooled by a 120mm fan and uses two independent power rails. Even though a lot of power supplies use two rails, this one in particular is basically two separate power supplies in one enclosure. One of them provides the 12-volt rail 1, and the 5-volt rail. The other provides the 12-volt rail 2 and the 3.3-volt rail. Each of these power supplies is a 500 watt power supply giving you the combined 1000. It is surprisingly quiet as the fan doesn’t even come on until 500 watts of power is being used. It uses a modular design. The pre-attached cables are your 24-pin motherboard cable, 8-pin EPS 12-volt, and two PCI-E 6+2-pin connectors that are compatible with 6-pin or 4-pin PCI-E video cards. If you’ve got two more graphics cards, you can plug in the optional PCI-E cables into the modular array. It also comes with two more 8-pin cables and two more 6-pin cables. If you do need to plug in 6 PCI-E cables, like you would need if using the 3 card SLI setup on the 790i board, then you can send a request to Corsair and they will send you the additional cables to make sure that the PSU will power whatever you need.
So the 790i is the ultimate platform combined with the ultimate PSU. The most powerful graphics solution that you can get with three graphics cards on one motherboard.