~ The Asus is unique among the tested SLI boards in providing 3 slots between the x16 PCIe slots used for SLI. All of the other SLI boards provide 2 slots between the video cards. This will be an important feature for users who water-cool their video cards or have special cooling in mind for the pair of SLI cards. ~ (From www.anandtech.com for ASUS A8N-SLI Deluxe review)

~ It offers two x16 PCIe slots, spaced far enough apart to accommodate even graphics cards with monstrous cooling solutions. ~ (From www.tomshardware.com for ASUS A8N-SLI Deluxe review)

 SATA on the Go (External SATA port on back I/O)
SATA on the Go designed for external SATA devices (ASUS exclusive)
The external SATA ports located at the back I/O provide smart setup, hot-plug and support up to 16 devices with port-multiplier functions. Easily backup photos, videos and other entertainment contents on external devices. 
ASUS P5ND2-SLI Deluxe supports the next-generation hard drives based on the Serial ATA (SATA) 3Gb/s storage specification, delivering enhanced scalability and doubling the bus bandwidth for high-speed data retrieval and saves. 

 AI Quiet 
Be Quiet when you value quietness 
With PCs serving as the entertainment centerpiece and playing a bigger role in our lives, quiet operation is in high demand. No one wants to hear the cooling fan spinning when watching a movie or listening to music. 
The ASUS AI Quiet function (Intel EIST plus ASUS Q-FAN2 technology) dynamically controls CPU speed and reduces temperature and fan speeds when peace and quiet are what you desire. (Note: ASUS AI Quiet function requires Intel 600 series CPU with EIST function) 

 Fanless Design 
Provide a cool environment without all the baggage
Cooling fans, though a popular thermal solution, also come with noise and malfunction likelyhood. ASUS Motherboard's fansless concept is specifically created to provide a cool environment without all the baggage. 
ASUS has devoted special efforts to address the thermal issues across the motherboard, and most notably the areas that reside the CPU, power, VGA, Northbridge and Southbridge. The heat sinks and strategic board layout were tailor made to dissipate heat in the most efficient manner. 

 Supports Intel® Single-Core 65nm Processors
This motherboard supports Intel® single-core 65nm intel® Pentium® 4/ Celeron® processors. ASUS motherboard is the ideal solution to enhance the performance of new generation processors.

 Dual-Core CPU
Enjoy the extraordinary CPU power from the latest dual-core CPU. 
The advanced processing technology contains two physical CPU cores with individually dedicated L2 Caches to satisfy the rising demand for more powerful processing capability.
(Refer to www.asus.com support site for Intel® Pentium D support list)

 Intel EM64T
64-bit computing, the next generation technology to replace current 32-bit architecture, delivers advanced system performance, faster memory access and increased productivity. This motherboard provides excellent compatibility and flexibility by supporting either 64-bit or 32-bit architecture.

 PCI Express Architecture
PCI Express is the latest I/O interconnect technology that will replace the existing PCI. With a bus bandwidth 4 times higher than that of AGP 8X interface, PCI Express x16 bus performs much better than AGP 8X in applications such as 3D gaming. PCI Express x1 also outperforms PCI interface with its exceptional high bandwidth up to 500MB/s. The high speed PCI Express interface creates new usages on desktop PCs e.g., Gigabit LAN, 1394b, and high-speed RAID systems.

 Precision Tweaker 
Precision Tweaker is designed for serious overclockers. It offers ways to raise system performance inch-by-inch and step-by-step to achieve maximum performance! This is about getting the most out of your machine, and taking pride in your customized computer. Precision Tweaker provides overclocking options for all major parts of the system: CPU, Memory, PCI-Express, and Front Side Bus.

 AI NOS™ 
Boost performance when you need it the most!
Applications such as 3D games and video editing demand a huge chunk of system resource. 
Inject "nitrous oxide" into your CPU! The patented AI NOS™ (Non-delay Overclocking System) technology intelligently detects system load and automatically boosts performance for the most demanding tasks. Unlike other dynamic overclocking techniques, AI NOS™ reacts much faster to satisfy your unending need for speeds. 

 PEG Link for dual VGA cards
Automatically gaming performance tuning for single/dual graphics cards
This latest technology, PEG (PCI Express Graphics) Link Mode, is a unique feature that enables users to boost graphics card performance for superior video quality. 
PEG Link allows users to raise GPU and VGA memory throughput via the motherboard BIOS the same way system bus and memory bus are tweaked. PEG Link Mode enables powerful video performance on DX8 and DX9 applications. ASUS engineers carefully fine-tuned the parameters for every single PCI-Express card to provide system stability during high-speed graphics operation.

 ASUS CPU Lock Free 
The P5ND2-SLI Deluxe offer the CPU Lock Free feature, which allows you to adjust CPU multiplier to 14x. The reduction of multiplier value provides more flexibility for increasing external FSB frequency to raise memory bus bandwidth. CPU Lock Free boosts overall system performance by making synchronous modification possible. Enjoy better performance at the same CPU operation speed and improve your system without pushing the CPU to the limit.

 C.P.R.(CPU Parameter Recall) 
When the system hangs due to overclocking failure, there is no need to open the case to clear CMOS data. Just simply restart the system, the BIOS would show the previous setting and then users can amend the CPU setting again.

 Dual Gigabit LAN & AI NET2 
The integrated dual Gigabit LAN design allows a PC to serve as a network gateway for managing traffic between two separate networks. This capability ensures rapid transfer of data from WAN to LAN without any added arbitration or latency. 
ASUS AI NET2 remotely detects cable connection the second you turn on the system, and any faulty connections are reported back up to 100 meters at 1 meter accuracy.

 Dual RAID 
The best solution to your RAID requirements on different storage standards. 
The NVIDIA MCP-04 Southbridge supports RAID 0, 1, 0+1, 5, and JBOD span cross 4 of Serial ATA 3Gb/s and 4 of Parallel ATA drives, totally up to 8 drives for RAID function.
The Silicon Image Sil3132 controller offers 2 additional SATA 3Gb/s interfaces and allows RAID 0 and RAID 1 functions for best data security. 

 ASUS Q-Fan2
ASUS Q-Fan2 technology intelligently adjusts both CPU fan and chassis fan speeds according to system loading to ensure quiet, cool and efficient operation.

 IEEE 1394
IEEE 1394 interface provides high speed digital interface for audio / video appliances such as digital television, digital video camcorders, storage peripherals & other PC portable devices. 

 NVIDIA DualDDR2 for high performance memory support
NVIDIA DASP 3.0: The third-generation DASP 3.0 (dynamic adaptive speculative preprocessor) consists of pre-processors that are tasked to track data threads and pre-fetch the appropriate data. It has been re-architected for improved performance and lowest latency. 
NVIDIA QuickSync: Designed to allow the use of the highest possible FSB and memory speeds without any negative impact on system performance. It features a patent-pending QuickSync synchronization technology that transfers memory requests and data between the FSB and memory clock domains in the shortest amount of time, thus maximizing system performance.

 NVIDIA ActiveArmor™ - Unmatched security
Dedicated hardware-based ActiveArmor secure networking engine and ActiveArmor Firewall protect your PC from hackers and spyware the minute it is turned on and filters out any unauthorized or suspicious traffic. NVIDIA ActiveArmor secures your PC against a wide range of attacks including IP-spoofing and ARP cache poisoning. Easy to set up and fast to configure, ActiveArmor offers remote secure access, monitoring, and configuration for management. 

 NVIDIA MediaShield™ - Advanced storage with RAID technology
Unique support for four SATA 3Gb/s and four ATA-133 drives. RAID 0, RAID 1, RAID 5, and RAID 0+1 support, enabling fast disk data transfers. Allows RAID arrays across both SATA and PATA hard drives and provides advanced features like the NVIDIA disk alert system that immediately alerts you if a drive fails, and dedicated spare disks that will automatically rebuild if a failed hard drive is detected.