Intel is updating its 'Presler' and 'Cedar Mill' 65nm desktop cores to improve the part's power consumption by adding support for the chip maker's Enhanced Intel SpeedStep Technology (EIST).

The upgrade affects the dual-core Pentium D 920, 930, 940 and 950, clocked at 2.8, 3.0, 3.2 and 3.4GHz, respectively. Sample of the updated core, dubbed 'C-1', will ship on February 24 with a view to product shipments coming through after April 5, documents seen by Reg Hardware reveal.

The effects on system builders will be minimal, according to Intel. The most noticeable change is that the 940 will consume on average 95W rather than 130W.

Intel also told customers it will be making the same change - from core-stepping 'B-1' to 'C-1' - to its Pentium 4 631, 641, 651 and 661 processors. That's no great surprise, since the 65nm Pentium Ds are made from two Pentium 4 6x1 cores connected together in the same chip package.

Again, the new single-core 65nm desktop CPUs will sample on February 24, but the first shipments of post-upgrade product aren't expected until April 12. By April 24, customers should be assured of receiving both C-1 Pentium 4 6x1 chips and C-1 Pentium D 9xx processors.

The new cores will also gain an "Enhanced HALT State" in addition to EIST. The single-core chips get a "Thermal Monitor 2". ®