This was an in-depth analysis of the enthusiast chipset offerings by Intel and Nvidia, and we came to a clear conclusion. Let me summarize what we found.
Both platforms provide a better feature set and more flexibility than any other chipset for the Intel architecture available today. Both have six Serial ATA/300 ports, offer at least two x16 PCI Express 2.0 slots for dual graphics setups (Nvidia offers a third), sufficient PCI Express and PCI connectivity (although Intel officially dropped PCI support), automatic configuration of memory speeds and timings via Intel XMP, and Nvidia SLI-ready memory (suitable RAM required). Both have a sophisticated storage subsystem and storage management solutions, which we found very useful. And both provide similar performance and overclock beyond the 500 MHz line (FSB2000). There are small advantages for the X48 chipset regarding performance and overclocking, but they don’t really count towards my conclusion, as no one will ever notice them. Both products are 90 nm based, hence the motherboard differences will be more substantial than the differences on the silicon level.
Those differences can be found in graphics support: while the Intel chipset will be maxed out with two ATI Radeon HD graphics cards, the Nvidia platform will work with up to three GeForce 8800 GTX or faster cards, or with the GeForce 9800 GX2 double deckers, effectively providing quad graphics for the enthusiast. If you’re up for this, then your only choice can be the Nvidia chipset. It is the more comprehensive solution and it includes two Gigabit ports as well as legacy UltraATA support; there is no way Intel’s X48 can beat that.
But the nForce 790i Ultra SLI does have some drawbacks, as well, which will not be relevant to the consumer, but will matter for professional users. There is Intel’s far superior storage performance in RAID configurations, which we found months ago with the ICH8 vs. nForce 680i comparison, and which hasn’t changed. I/O performance and RAID throughput is only average on the nForce 790i Ultra SLI, so if you intend to create a workstation, you better go with the X48.
Finally, Nvidia’s more comprehensive PCI Express support for graphics comes at a price: the entire system required 10 watts more power than the Intel solution, although this won’t be a criterion for a $250+ motherboard. If you don’t need dual PCI Express graphics, then Intel’s upcoming P45 chipset could be an even better choice.