Where PCI Express is concerned, the X38 has an advantage over all of its competitors : it is the first chipset to support the PCI Express 2.0 standard. However, this only applies to the two x16 PCIe slots - the four x1 slots and the single x4 slot are attached to the South Bridge of the ICH9 and are therefore still limited to PCI Express 1.
With PCI Express 2.0, the frequency of the serial pathways doubles from 2.5 GHz to 5 GHz, giving each PCIe lane a 500 MB/s transfer rate. This is true not only for the graphics card, but any component that uses the new interface, be it a network controller or a sound card.
By the time cards appear that are actually able to utilize this bandwidth, Intel will probably already have introduced newer chipsets. Thus, at this point the PCI Express 2.0 interface is a nice addition, but doesn’t really contribute to future proofing the board per se.
Overclocking With DDR3 Memory
Another new technology that Intel is introducing with the X38 is the XMP specification. The principle is similar to that of the SLI memory specification jointly introduced by AMD and Nvidia over a year ago on the Socket AM2 launch in May 2006. It would appear that this technology was, let’s say, inspired by AMD.
The principle is very simple : memory manufacturers program the frequencies at which their module will operate when overclocked into the SPD. This would also include the timing parameters. However, XMP has one major disadvantage : unlike AMD’s solution, it only works with DDR3 memory, and then, only with those modules that specifically support XMP. As Intel’s launch partner, Corsair will be the first company to offer such modules.
We compared the prices of the cheapest DDR2 and DDR3 memory modules with 1 GB capacity :
- DDR3-1066 - $226 (CL7, OCZ Gold)
- DDR2-800 - $38 (CL5, Aeneon)
With such an extreme price difference, it is obvious that the vast majority of users will choose DDR2. Assuming that XMP-certified DDR3 modules will cost even more, since they need to run at higher frequencies, this feature is currently not an incentive to buy an X38 board.
When DDR3 memory is overclocked, its latencies rise immensely, negating any possible performance boost. The Conroe architecture of the Core 2 microprocessor is optimized for minimal memory access, which is why the current incarnation sports up to 8 MB of L2 cache. The 45 nanometer Penryn CPUs will even contain 12 MB of L2 cache. As a result, the memory will have even less impact on possible performance gains.
As was the case with the P35, motherboard makers are taking a wait-and-see approach for now, due to the limited attractiveness of DDR3, and producing only X38 boards with DDR2 support. This is also true for Gigabyte, the company that provided our X38 review sample. Thus, the XMP functionality is also of only limited importance right now.