The Asus P55T2P4 has two jumpers for adjusting the clock multipliers. As the board is only equipped with the jumpers BF0 and BF1, the maximum multiplier of 3.5 was just enough to operate a Pentium MMX 233 from 1997 with the setting 3.5 x 66 MHz = 233 MHz. There are two possibilities to achieve higher clock rates for the CPU frequency: One method is to increase the system clock to 75 MHz or even 83 MHz, as described above. Additionally AMD's processors with CXT core offer the option of chosing a multiplier of 6. To utilize this option the multiplier on the motherboard must be set to 2.0, which the processor then translates into factor 6. Therefore 66 MHz allow a maximum clock frequency of 400 MHz (6 x 66 = 400 MHz). Now the Asus P55T2P4 can accommodate an AMD K6-2+/500 if the system clock is increased to 83 MHz (6 x 83 MHz = 500 MHz). Real freaks could also drive the system clock to almost 90 MHz by exchanging the quartz of the clock generator (substitute the 14.83 MHz quartz with a 15 MHz model). In this case the PCI bus runs at 45 MHz, which is a problem for most components, however.
The Asus P55T2P4 only has the jumpers BF0 and BF1 allowing a maximum possible clock multiplier of 3.5. But the AMD K6-2+ interprets the multiplier "2" as 6.
This table lists all possible clock multipliers.
|CPU Clock||FSB and Multiplier||PCI Clock|
|500 MHz||6 x 83 MHz||41.5 MHz|
|450 MHz||6 x 75 MHz||37.5 MHz|
|400 MHz||6 x 66 MHz||33.3 MHz|