Back in May, Intel launched the P35 Express chipset, a replacement for its popular 965P. Classified as a mid-range product, the P35 added official support for front-side bus speeds up to 1333MHz, came bundled with a new ICH9R south bridge chip, and became the first desktop chipset to support DDR3 memory. Enthusiasts lapped it up, and in the months since, we've seen a wave of P35 motherboards that offer great performance and tantalizing overclocking potential.
Intel's mid-range chipsets have traditionally been excellent, so the P35's success wasn't a surprise. That success also raised expectations for Intel's new high-end core logic chipset: the X38 Express. This isn't a new trend; the all-around goodness typical of Intel's mid-range chipsets has long made it difficult for the company's flagship offerings to shine.
Topping the P35 Express won't be easy, but Intel has a few tricks up its sleeve with the X38. Chief among them is next-gen PCI Express 2.0 connectivity—a first for desktop chipsets—with enough lanes for dual-x16 CrossFire configurations. As is customary for its high-end chipsets, Intel has also rolled out memory controller optimizations that promise faster performance and support for higher DDR3 memory speeds.
To find out whether these perks are enough to elevate the X38 Express over its blue-collar P35 sibling, we've run the first X38 boards from Asus and Gigabyte through a relentless series of memory controller, application, and peripheral performance tests. Read on to see how the X38 fares and what you can expect from the first wave of motherboards based on this new chipset.
Introducing the X38 Express
The meat of the X38 Express is in its north bridge chip, which is what sets it apart from the P35 Express. Intel's engineers have built several optimizations into the X38's memory controller, including what Intel calls a "flexible clock crossing architecture" and improved prefetching circuitry. Those optimizations aim to make the X38's memory controller quicker than that of the P35, which is a tall order considering how aggressively motherboard makers push memory performance on their mid-range boards.
Still, the X38 can count official support for DDR3 memory speeds up to 1333MHz as one advantage over the P35. That chipset only supports DDR3 memory up to 1066MHz, which is, well, slower. Thanks to rather quickly ramping DDR3 memory speeds, a number of DDR3-1333 modules are on the market and ready to take advantage of the X38, as well.
In addition to supporting faster DDR3, the X38 chipset can take advantage of memory modules that feature Extreme Memory Profiles, or XMP. XMP adds additional memory timing and clock speed profiles to DDR3 memory, much like Enhanced Performance Profiles (EPP) do for DDR2 memory. These profiles make it easier for less experienced users to tune or even overclock their memory through a series of profiles rather than forcing them to manipulate individual timings and bus speeds.
DDR3 memory prices remain high, though, with 2GB kits costing more than double that of their DDR2 counterparts at the same speed grade. Fortunately, the X38 also supports DDR2, providing motherboard makers with a measure of flexibility and end users with the opportunity to save quite a lot of money when putting together a new system. You probably won't find many X38 boards with both DDR2 and DDR3 memory slots, but we expect mobo makers to offer variants of their boards that support each. With the P35 Express, those models typically used the same basic board design, save for the DIMM slots.
X38 Express P35 Express nForce 680i SLI SPP
Front-side bus 1333/1066/800MHz 1333/1066/800MHz 1333/1066/800MHz
Memory controller DDR2-800/DDR3-1333 DDR2-800/DDR3-1066 DDR2-800
PCI Express lanes 32* 16 18
Multi-GPU support CrossFire CrossFire* SLI
Chipset interconnect DMI DMI HyperTransport
Peak interconnect bandwidth 2GB/s 2GB/s 8GB/s
