BX-133 Video Guide

Memory- Another problem forgotten

The second item on the BX 133 problem list was the memory interface. Along with the introduction of the 440BX chipset, a new memory type was beginning to take form. PC100 SDRAM chips were necessary to work at the motherboard's stock 100 MHz front side bus. Since the memory interacts with the rest of the computer without the use of any divider, the memory actually runs at the FSB's speed. Although PC100 SDRAM modules had no problem running at the 100 MHz specified speed, problem began to arise when the FSB (and subsequently the memory) was pushed to 133 MHz.

No longer did the rated 100 MHz suffice for performance. Running the 100 MHz RAM at 133 MHz caused all sorts of problems. Since RAM quality and maximum speed varies by batch, some overclockers were left buying RAM module after RAM module until one DIMM performed properly at the 133 MHz speed. After a bit of time, some companies became known for producing SDRAM chips that could usually hit the 133 MHz limit.

As discussed in our PC133 Memory Roundup, it was VIA's Apollo Pro 133A chipset that originally called for a new memory standard to be produced. Since Intel refused to accept the need for PC133 SDRAM, due to the fact that all of the official 133 MHz FSB solutions used either RDRAM or PC100 SDRAM, VIA actually introduced the PC133 standard into the industry. By working with memory producers, PC133 SDRAM was quickly adopted, especially when Intel revised their roadmap to allow for the i815 to use PC133 SDRAM.

With the introduction of the PC133 standard, users could rest assured that their RAM would function correctly with a 133 MHz FSB speed. No longer would out of spec memory speeds cause system crashes or corruption, removing yet another problem from our potential BX-133 road blocks.

On a related note, we have heard of some problems running 440BX boards at 133 MHz with certain RAM configurations. In the lab we have duplicated these results by using two or more Corsair Infineon DIMMS as well as two or more Micron -7e DIMMS. In this test, we used Mushkin Nanya RAM, Memman Infineon RAM, and Corsair Toshiba RAM. Each stick worked fine by itself as well as in any combination with other sticks when at 133 MHz. When the FSB was pushed to 148 MHz, the 2 DIMM configuration worked fine however using all 3 DIMMs resulted in problems.