New Chipsets: 925X, 915G, 915P, 915GV
Let's get rid of the code names first. Alderwood is officially called 925X Express Chipset and is the successor to 875P (aka Canterwood). The latter will not be phased out before the end of the year, however. With a price point of at least $ 50 per 1,000 units, the 925X is the premium chipset for the new LGA 775 architecture.
The code name Grantsdale covers three chipsets: 915G with Intel's Graphics Media Accelerator 900 integrated graphics, 915P for discrete graphics and 915GV, a low-cost integrated graphics version without the option to upgrade discrete PCIe graphics (Intel calls that PCI Express Graphics or PEG). Together they are the 915 Express Chipset family and follow the 865 product line, known as Springdale.
None of the new chipsets supports AGP, but either DDR2 or DDR1 memory can be used. The memory used depends on the availability of memory sockets, which in turn is up to the motherboard makers.
No company is going to introduce the 925X premium chipset with support for DDR1 memory, so this platform will definitely be DDR2 only. In contrast, we expect to see lots of 915G/P motherboards either with sockets for both DDR2 and DDR1 memory or one of these types. However, the availability of different memory sockets does not bridge for the technology gap: You can't mix DDR1 and DDR2, and according to our experience with former memory technology transitions, it wouldn't be a wise thing to do performance-wise.
As is customary, Intel splits their core logic products into two building blocks for scalability. The chipset names mentioned above refer to the memory controller hub or MCH (also known as Northbridge), which consists of the graphics interface and the memory controller. Here, the Accelerated Graphics Port or AGP is being replaced by a x16 PCI Express interface that delivers four times the bandwidth. The second fundamental change is that the memory controller now supports DDR2-400 and DDR2-533 memory in addition to conventional DDR400 RAMs. Also, all of the new chipsets are dual channel types.
A Southbridge is needed to pair with the Northbridge, and Intel calls it the ICH (I/O Controller Hub). Here you can find all the interfaces and neat features that make the difference between a top-notch computer and a lame duck.
875P vs. 925X/915