Mainboard Makers Offer Advanced Overclockability Options

Mainboards Propose to Alter CPU Multiplier

by Anton Shilov
11/10/2004 | 02:29 PM

Leading mainboard makers, ABIT, ASUS, Gigabyte and MSI, propose to adjust multiplier settings of Intel’s central processing units in order to achieve higher system performance when overclocking on their latest breed of mainboards. However, not all the mainboards and not all the microprocessors can really benefit from the technologies.

 

Intel’s Pentium 4 processors based on the Prescott core that have TDP of 115W or higher can automatically reduce clock-speed by altering CPU multiplier when mainboards cannot supply enough power to the central processing units. Mainboard makers like ABIT, ASUS, Gigabyte and MSI, however, allow to modify multipliers on certain mainboards manually, which delivers advanced overclocking options.

CPU frequency is calculated by its multiplier multiplied on the processor system bus. While historically neither of those two constituents were strictly set, Intel has locked CPU multipliers in the late nineties for all of its Intel Pentium II, Intel Pentium III, Intel Pentium 4 and Intel Celeron processors. As a consequence, overclockers had to increase processor system bus to increase clock-speeds.

Since clock-speeds of AGP, PCI and PCI Express buses are determined by special dividers that divide clock-speed of PSB, overclocking of system bus stressed system components along with the chip itself, as PC infrastructure is also certified to work only on designated speeds of PCI, AGP and other buses. While some chipsets can dynamically adjust such dividers, locked CPU multiplier still somewhat restricted overclocking capabilities of microprocessors, particularly on Intel chipsets, which could not alter bus dividers without special tweaks from mainboard makers.

Thanks to the “multiplier indulgence” for the Prescott processors, mainboard makers can offer altering of CPU multiplier down to 14x or up to CPU original multiplier. This allows end-users to obtain more flexible overclocking. Furthermore, if users are lucky enough, they can set the Pentium 4 chips designed for 800MHz infrastructure to work on 1066MHz bus by setting 14x multiplier and receiving 3.73GHz clock-speed, not a huge uptick from typical high-end Pentium 4 speed of about 3.20GHz to 3.60GHz.

ABIT calls it capability to unlock CPU multiplier “CPU Accelerator” and currently enables it, just like other manufacturers on Socket 775 mainboards based on i915- and i925X-series as well as on Socket 478 mainboards powered by i875P and i865PE chipsets.

Unfortunately, Intel’s latest stepping of Prescott processors – E0 – cannot unlock multiplier. It is unclear whether mainboards that can unlock multiplier from ABIT, ASUS, Gigabyte and MSI. Furthermore, far not all mainboards and memory controller hubs that power them can achieve substantial PSB overclocking.