To run Quad SLI in your system, you will need to meet the following requirements:

1. Your motherboard will require double-wide slot spacing between PIC Express slots.

Any of our P55 and X58 series boards will support Quad SLI

2. The video card will need to be Quad SLI ready.

Currently they are:
EVGA GTX 295 (https://www.evga.com/articles/00478/)
EVGA 9800 GX2 (https://www.evga.com/articles/395.asp)
EVGA 7950 GX2 (https://www.evga.com/articles/310.asp)

3. You will need a Quad SLI ready power supply.

Please refer to SLI Zone for a list of the certified power supplies that will support Quad SLI.  Look under "Certified Products" -> "Power Supplies" Specifically, look for the ones that will support "Dual GeForce 9800GT2".

4. You will need to use either Windows® Vista (all editions) or Windows® 7 (all editions)

If you do not meet any of these requirements your system will give you issues when setting it up for Quad SLI.