ASUS uses a full sized ATX board measuring 30x30cm and uses 6 layers in order to route all of the trace wires for the nForce 4 SLI x16 Intel chipset, as extra wires are now used.
The first thing we want to mention is this board's power features. ASUS has gone all out to give this board a clean and stable power profile. The P5N32-SLI uses a 6 phase voltage regulation system. With the Pentium Extreme Edition now supported on the P5N32-SLI series, 150 watts of power is going to be needed for just standard speeds but what happens when overclocking - a 4 phase would simple go completely out the window.
ASUS on its last series of enthusiast boards did a perfect job of placing the connectors for cables so that the board manages to achieve the best air flow profile. The P5N32-SLI also inherits this quality. The 24-pin ATX power connector is located at the right hand side of the board along with the two IDE ports and FDD port. An 8-pin EPS power connector is located at the top of the board just behind the PS/2 ports.
You can also see in this photo the extensive heatpipes that ASUS use to cool the board. The pipes go from the Northbridge to the left most Mosfets heatinks, the Southbridge pipe goes to the upper most Mosfet sinks. If you choose to go water cooling, the two fans we showed earlier are for installing onto the top of the Mosfet heatsinks. When using conventional air cooling, the additional fans aren't required.
The expansion slots are very extensive. First off you have two PCI-E x16 slots, both running at full x16 speeds. This allows for the use of nVidia SLI video cards to both run at full speed PCI-E. There are also two PCI-E x1 slots for adding in additional devices like TV Tuners, SATA controllers and other devices to show their faces on the market. There is also one PCI-E x4 slot, these are normally only found on server boards for SAS, SCSI and high powered SATA controllers. Lastly there are two PCI slots for legacy support until PCI-E fully takes over PCI's ability to support all devices on the market.
The rear I/O ports are somewhat non-standard, but then again, these days every motherboard manufacturer has their own layout. Most of the normal ports are there, PS/2, Parallel and USB are all present. What is different is the e.SATA port. While at a press conference with Seagate recently, we learnt that with the new SATA 2.5 spec, external Serial ATA will soon make its presence felt, and the e.SATA port that ASUS has put on the back plane is what will be used to connect e.SATA to the main system. The e.SATA port runs off a separate SATA controller chip onboard.
The nForce 4 SLI x16 Intel Edition is a two chip solution, like its younger brother. The new chip supports two full speed PCI Express x16 slots for SLI, which means no more paddle card to set SLI mode and this is achieved very simply. The Northbridge has 16 PCI Express lanes which are routed to the blue PCI-E x16 slot. The Southbridge has 24 PCI Express lanes, 16 of these are set to an additional PCI-E x16 slot on the board (the black one). The rest of the lanes are used for the expansion slots on the board.
Apart from additional PCI-E lanes, the Southbridge's features remain unchanged from the original Intel NF4 chipset. The Northbridge has been re-worked in order to support the Intel Pentium Extreme Edition CPU's, something the original NF4 chipset would not properly do. The Northbridge and Southbridge are connected together using AMD's Hyper Transport Technology at the same speed that AMD uses to connect its Athlon 64 to external chipsets, however, the multiplier is only at 3x giving over 6GB/s of data transfers.
Gigabit Ethernet is now a standard feature of modern motherboards, and dual Gigabit is now becoming an even greater feature. The P5N32-SLI features a Dual Gigabit setup. First you have the onboard nVidia nForce4 Gigabit LAN with the Marvell 88E1111 PHY controller chip with built in Firewall function. The final Gigabit controller is a PCI-E Marvell 88E4035 controller chip.
Firewire controllers are now common place. The Texas Instruments PCI based IEEE-1394 controller gives two Firewire-400 ports.
Silicon Image controllers are now showing up on motherboards as the expansion chips of choice. ASUS has put the SIL3132 PCI-E controller chip onboard to give two extra SATA ports. One port is located above the top PCI-E x1 slot and the second port is routed to the e.SATA port.