Intel this week quietly launched its anticipated 975X Express desktop chipset, pitched at the dual-core Pentium Extreme Edition processor.

As expected, the 975X builds on the company's existing PEE chipset, the 955X. Like its predecessor, it has support for twin graphics cards, this time connecting to the North Bridge across two PCI Express 8x slots. The 16 PCI-E lanes can also be configured into a single 16x slot. The 955X has a single 16x slot and a 4x slot.

Intel doesn't say whether it's compatible with Nvidia's SLI and/or ATI's CrossFire. However, mobo makers who have announced products based on the part have claimed that ATI's multi-GPU technologies is supported by the chipset.

Like the 955X, the 975X supports frontside bus clock speeds of 800MHz and 1066MHz. It provides a dual-channel DDR 2 SDRAM memory interface supporting RAM clocked at up to 667MHz effective. The ICH7R South Bridge supports four 3Gbps Serial ATA ports with RAID 0, 1, 5 and 10. There are six PCI-E lanes and support for six PCI slots, plus eight USB 2.0 ports. The chipset supports Intel's HD Audio system. The 975X also has some other "tweaks" to lift it above the 955X, sources close to the chip maker told us.

Intel hasn't formally announced the 975X, even though motherboard makers have begun to announce products based upon it. Most recently, Foxconn introduced the 975X7AA-8EKRS2, due to ship next month. Gigabyte's GA-G1975X shipped this month. ®