Closer Look: 925XE Express

Since Pentium 4 XE 3.46GHz processor is the first CPU to support 1066MHz system bus, we had to use a mainboard based on a new chipset, which allows clocking the bus at this frequency. Intel decided to take the easiest way and didn’t develop any special sets of core logic for its new Pentium 4 XE 3.46GHz processor. The next generation chipsets, namely Lakeport and Glenwood, supporting 1066MHz bus and the whole bunch of other features are to come out only in the middle of next year. In the meanwhile, Intel adapted its already existing i925X Express chipset for the needs of the new Pentium 4 XE 3.46GHz processor. The new chipset version is called i925XE Express and its only difference from the predecessor by the new faster system bus support. Intel didn’t even include DDR2-667 SDRAM support in the specs of the i925XE Express, although unofficially this chipset should be able to work with this memory when the bus frequency is set to 1066MHz.

Note that speeding up the bus between the CPU and the chipset to 1066MHz, resulted into higher bandwidth of the bus between the processor and the system memory. Namely it grew from 6.4GB/s to 8.5GB/s. Moreover, when the system bus is clocked at 1066MHz and the DDR2 memory is working at 533MHz, the CPU bus and the memory bus work synchronously, which as a rule allows minimizing the chipset North Bridge latencies.

i925XE chipset is fully compatible with i925X and doesn’t require any new PCB layouts or wiring. Therefore, the mainboards based on the new chipset, which was released only because of one single CPU, will hardly take long to appear in the market. However, despite the minor differences from the i925X, the overclocking fans will be able to benefit from the new core logic a bit more. Due to the official support of 1066MHz bus, mainboards on i925XE Express should definitely be much more stable when working with the bus frequency exceeding 800MHz, than any of the older LGA775 solutions. So, i925XE Express has every right to be considered a great solution for hardware enthusiasts who are willing to spend quite a bit of money on the new Pentium 4 XE 3.46GHz. At the same time, it is also an excellent overclocker’s choice, which has already been proven by the first benchmark results for the mainboards based on the new core logic set.

To prove that the i925X and i925XE are identical solutions, let me give you the following example. Intel’s own mainboards, such as Desktop Board D925XCV2 and Desktop Board D925XECV2 based on them are built on the same PCB and even use the same BIOS code.

However, if you try to install the new Pentium 4 XE 3.46GHz into the older Intel D925XCV2 Desktop Board based on i925X chipset, you will hardly succeed in making the system work: i925X based mainboard will not even start with the new processor, even if you reflash the BIOS supporting it from the newer D925XECV2. So, I think I can conclude that there are still some hardware differences between the i925XE and the older i925X.