BX at 133MHz

As we mentioned in our RDRAM Performance article, the BX chipset is now capable of running, albeit unofficially, at the 133MHz FSB frequency.  What has changed since May 1998 that allows for a BX motherboard to run at 133MHz?

For one thing, motherboard manufacturers have been tweaking their designs quite a bit over the past two years.  The BX motherboard platform in general is at the point where you shouldn't have to worry too much about variations in performance or stability when going from one motherboard to the next.  This perfection of the motherboard design, especially from the companies that have had quite a few BX boards (i.e. ASUS, ABIT…) has made their reliability at higher FSB frequencies much more of a reality and less of a dream.

Secondly, the PC133 memory standard has been completed and implemented by VIA as well as refined by Intel.  There is finally memory available that was designed with a 133MHz operating frequency in mind, and not too long ago Micron began shipping their –7E parts, which are officially rated at 133MHz CAS2, which provides for an additional 5 – 10% performance improvement over 133MHz CAS3. 

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Finally, video card manufacturers have been designing their video cards to operate at a greater range of frequencies that remain outside of the 66MHz AGP specification. 

A combination of all three of these factors has made it possible to run BX motherboards at the 133MHz frequency, even without the presence of a 1/2 AGP clock divider (there would have to be a revision of the BX North Bridge in order to add support for that divider).  Now, not all BX motherboards are capable of running at the 133MHz FSB, but there is definitely a high chance of it working on the latest BX motherboards, especially those produced by such companies as ABIT, ASUS, AOpen, and MSI, to name a few. 

Index Ultra DMA 66 on a BX?

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