The Pentium D's companion: Intel's 945 Express chipsets
Intel's dual-core chips won't work without a new core-logic chipset, so naturally, the Pentium D is arriving with a couple of friends, the 945P and 945G Express chipsets. Yes, Intel has retained the dorky "Express" in the name of the chipsets to remind everyone that these puppies support PCI Express. Fortunately, they've also retained all the snazzy features of the 915/925 Express series, including dual channels of DDR2 memory, High Definition Audio, and all the rest. We recently looked at the high-end, enthusiast-oriented 955X chipset in our Pentium XE 840 review. The 945 series is a higher volume, lower priced version of the 955X with most of the same features. There are, however, two versions of the 945: the 945G with integrated graphics, and the 945P without.

Like the 955X, the 945 series can handle front-side bus speeds up to 1066MHz and DDR2 memory up to 667MHz, but the 945 is missing what Intel calls Memory Pipeline Technology. Under this fancy marketing name lies a rather commonplace reality: Intel is binning its north bridge chips, picking out the ones that most eagerly run with tighter timings in the memory controller and selling those as 955X chips. Everything else becomes a 945P. This segmentation of north bridges is familiar from the 915/925 series and from the 865/875 products before that. The 955X will perform a little bit better than the 945, and it will cost a little more. The primary speed difference between the two will come in the form of imperceptibly higher memory access latencies on the 945 series. We'll quantify that difference in our benchmarks.

The 945 series' ability to support DDR2 667 memory may be most beneficial to the performance of the 945G, whose built-in graphics core will have access more memory bandwidth. In the 945G, Intel has massaged the GMA 900 graphics core from the 915G and given it a new name, the GMA 950. The GMA 950 still has a four-pipe design, but clock speeds are up from 333MHz to 400MHz. These tweaks are sufficient for Intel to claim a 100% performance improvement over the GMA 900 in 3DMark05. The GMA 950 also adds the ability to connect to a media expansion card, useful for such things as adding a TV tuner to one's system. (The 945P lists for $38 in quantities of 1000, and list price on the 945G in 1K quantities is $42. So the price of a GMA 950 is effective $4. That, folks, is how Intel got the be the world's #1 graphics supplier in terms of volume.)

The other end of the chipset equation has changed, too, with the introduction of Intel's ICH7 and ICH7R south bridge chips. The ICH7 series has two more PCI Express lanes than the ICH6, bringing the total up to six. Both ICH7 chips also support Serial ATA's new 300MB/s transfer rates (or 3Gb/s, if you must), but only the ICH7R has Intel's Matrix Storage. The Matrix Storage package includes RAID capabilities, new RAID levels 5 and 10, and support for the AHCI specification. Without AHCI, the non-R version of the ICH7 will be devoid of support for Native Command Queuing (NCQ) and hot-plugging of devices. For that reason, I'd expect even some mid-range 945P-based motherboards to use the ICH7R, as Intel's D945GTP does.