This is what I need, according to Crucial's website.
* Chipset: nVidia nForce 680i SLI
* Supported DRAM Types: DDR2 SDRAM only
* Module Types Supported: Unbuffered only
* Error Detection Support: Non-ECC only
* Graphics Support: Dual PCI Express x16, SLI capable
* Max Component Density: 1024
* USB Support: 2.x Compliant
* 240-pin DDR2 DIMM Banking: 4 (2 banks of 2)
* DDR2 SDRAM Frequencies: PC2-4200, PC2-5300, and PC2-6400
* Max Unbuffered DDR2 SDRAM: 8192MB
* Although the memory can be installed one module at a time, the best performance comes from using matched pairs of modules.
Number of Slots:
Slot 1
Slot 2
Slot 3
Slot 4
Each memory slot can hold DDR2 PC2-6400,DDR2 PC2-8500,DDR2 PC2-4200,DDR2 PC2-5300 with a maximum of 2GB per slot.*
*Not to exceed manufacturer supported memory.